Legion III. NASSELLARIA, (continued 6)

1. Perispyris bicincta, n. sp. (Pl. 88, fig. 13).

Shell smooth, with two deep transverse annular strictures and a deep sagittal incision at the sternal base; one and a half times as long as broad. Cephalis nut-shaped, with large irregular roundish pores and very broad bars. Everywhere from its surface there arise numerous slender arborescent radial beams; by the anastomoses of their ramified branches there arise the flat cap-shaped cupola and the larger bilobed thorax; and also the external enveloping shell with loose delicate network.

Dimensions.—Inner shell 0.17 long, 0.1 broad; outer shell 0.23 long, 0.17 broad; ring 0.06 long.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

2. Perispyris spongiosa, n. sp.

Shell rough, with two distinct transverse strictures and a deep sternal incision, similar to the preceding; the radial beams arising from the inner shell, and forming by anastomosing branches the outer shell, are thinner and more numerous, and the framework of the latter on the surface is very dense and spongy, therefore the shell is dark and not transparent.

Dimensions.—Inner shell 0.18 long, 0.12 broad; outer shell 0.24 long, 0.18 broad; ring 0.08 long.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

3. Perispyris lentellipsis, n. sp. (Pl. 88, fig. 12).

Shell smooth, lentelliptical, with three different isopolar axes, perpendicular one to another. Transverse and sagittal strictures are wanting; but the large enclosed ring and the two pairs of large adjacent annular meshes indicate clearly the position and size of the hidden cephalis. The two other joints (the cupola on the upper and the thorax on the lower pole of the cephalis) are nearly equal, cap-shaped or hemispherical. The outer lentelliptical shell is little larger than the inner, connected with it by numerous thin bristle-shaped radial beams, and exhibits a delicate arachnoidal lattice-work.

Dimensions.—Inner shell 0.15 long, 0.1 broad; outer shell 0.18 long, 0.13 broad; ring 0.08 long.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

Subfamily 3. Nephrospyrida (vel Paradictyida, Haeckel, 1881).

Definition.—Androspyrida without free basal feet and external constrictions. Shell either spherical or discoidal.

Genus 484. Sphærospyris,^[102] n. gen.

Definition.—Androspyrida with a spherical or subspherical shell, without basal incision and transverse constriction; without free basal feet.

The genus Sphærospyris differs from all other Spyroidea in the regular spherical or spheroidal form of the lattice-shell. It may therefore be easily confounded with some species of the Sphæroidea; but the internal sagittal ring, placed in the median plane of the fenestrated sphere and connected with it by radial beams, leaves no doubt that it is derived from a true Spyroid, either Dictyospyris or Amphispyris, or another genus. Sometimes also four larger collar pores are visible.

1. Sphærospyris sphæra, Haeckel.

Dictyospyris sphæra, Bütschli, 1882, Zeitschr. f. wiss. Zool. vol. xxxvi. pp. 511, 539, Taf. xxxii. fig. 15, a, b.

Shell smooth, nearly spherical, slightly flattened at the base, with small regular circular pores. In the centre of the basal plate a regular rectangular cross with four equal collar pores.

Dimensions.—Diameter of the shell 0.11, of the enclosed ring 0.06.

Habitat.—Fossil in Barbados.

2. Sphærospyris quadriforis, n. sp.

Shell rough, nearly spherical, slightly flattened at the base, with small regular circular pores. In the centre of the basal plate a bilateral symmetrical cross with four ovate collar pores; two cardinal pores twice as large as the two jugular pores and six to eight times as broad as the other shell-pores.

Dimensions.—Diameter of the shell 0.26, of the enclosed ring 0.09.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

3. Sphærospyris globosa, n. sp. (Pl. 83, fig. 4).

Shell smooth, perfectly spherical, with small subregular circular pores. In the centre of the basal plate no larger collar pores. (The original collar pores are here of the same size as the other pores, and cannot therefore be distinguished.)

Dimensions.—Diameter of the shell 0.13, of the enclosed ring 0.06.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

Genus 485. Nephrospyris,^[103] Haeckel, 1881, Prodromus, p. 444.

Definition.—Androspyrida with a discoidal, kidney-shaped, or subcircular shell, with a basal incision; without transverse constriction and free basal feet.

The genus Nephrospyris is one of the most peculiar and most modified of the Spyroidea, of extraordinary size, in this respect surpassing all other genera of this suborder, and differing from them in its flat discoidal form. The diameter of the compressed shell often reaches one half millimetre or more; its perimeter is elliptical or nearly circular, smooth, constantly with a characteristic deep sternal incision or a basal sinus on the basal pole of the main axis. The central sagittal ring is comparatively small. The margin is often inflated like a delicate reticular girdle, and contains a large number of peculiar spherical or roundish nucleated cells (Pl. 90, figs. 6-10). According to the observations of Dr. John Murray, made on living Nephrospyris, they are Vorticellina, perhaps constant Symbiontes.

Subgenus 1. Nephrodictyum, Haeckel, 1881, Prodromus, p. 444.

Definition.—Network of the shell simple, with bars of nearly equal breadth.

1. Nephrospyris renilla, n. sp. (Pl. 90, figs. 9, 10).

Shell kidney-shaped, one and a half times as broad as long, and three times as long as the deep kidney-shaped sternal incision. Ring with six pairs of branched apophyses, the bars of the apical pair vertical, of the basal pair divergent. The corresponding bars of the two middle pairs (on the frontal and the occipital face) form together on each side a large pentagonal or hexagonal naso-orbital area, which is surrounded by four or five large polygonal meshes; the other meshes become smaller towards the inflated margin. All meshes simple, without arachnoidal framework.

Dimensions.—Shell 0.3 to 0.4 long, 0.4 to 0.5 broad; ring 0.08 to 0.1 long.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

2. Nephrospyris nephridium, n. sp.

Shell kidney-shaped, one and two-third times as broad as long, very similar to the preceding species (or only a variety of it?). Ring with seven pairs of branched apophyses. The large naso-orbital area is on the dorsal or occipital side simple, on the ventral or facial side divided by an equatorial pair of transverse horizontal branches into two superior orbital, and two inferior nasal holes. Sternal incision ovate. All meshes simple.

Dimensions.—Shell 0.25 to 0.35 long, 0.4 to 0.5 broad; ring .007 to 0.08 long.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

3. Nephrospyris phaseolus, n. sp.

Shell kidney-shaped, twice as broad as long, very similar to the two preceding species (or only a variety of them?). Ring with eight pairs of branched apophyses. The large naso-orbital area (between the mitral and collar ring) is on the dorsal and on the ventral side divided by two equatorial pairs of horizontal branches into two superior (orbital and occipital), and two inferior (nasal and suboccipital) holes. Sternal incision cordate. All meshes simple.

Dimensions.—Shell 0.25 long, 0.5 broad; ring 0.06 to 0.07 long.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

4. Nephrospyris cordata, n. sp.

Shell heart-shaped, about as long as broad. Ring with six pairs of branched apophyses (as in Nephrospyris renilla, Pl. 90, fig. 9). No equatorial transverse branches. Sternal incision cordate, deeper than in all other species of the genus, nearly half as long as the shell. All meshes of the network simple.

Dimensions.—Shell 0.32 long, 0.36 broad; ring 0.05 to 0.06 long.

Habitat.—Central Pacific, Station 263, depth 2650 fathoms.

Subgenus 2. Paradictyum, Haeckel, 1881, Prodromus, p. 444.

Definition.—Network of the shell double; the larger meshes separated by strong bars, and filled up by a very delicate secondary arachnoidal network.

5. Nephrospyris paradictyum, n. sp. (Pl. 90, figs. 1-8).

Paradictyum paradoxum, Haeckel, 1881, Prodromus et Atlas, loc. cit.

Shell nearly circular, ten times as broad as the inflated marginal girdle, and three times as long as the sternal incision. Ring with six pairs of branched apophyses; the bars of the apical pair nearly vertical, of the basal pair divergent; the corresponding and opposite bars of the two middle pairs (on the occipital and on the frontal face) form together a large middle naso-orbital area; above and below this lie six pairs of larger meshes. All larger meshes of the network are filled up by very delicate arachnoidal framework. The inflated and delicately reticulated marginal girdle of this and of the following closely allied species is usually filled up by nucleated roundish cells (fig. 7), which are Vorticellinæ, according to the observations of Dr. John Murray on living specimens.

Dimensions.—Diameter of the shell 0.5 to 0.6, of the marginal girdle 0.05 to 0.07; ring 0.07 to 0.09 long.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

6. Nephrospyris paradoxa, n. sp.

Shell kidney-shaped, one and one-third times as broad as long, six times as broad as the inflated marginal girdle, and half as long as the sternal incision. Ring with six pairs of apophyses. Above and below the large naso-orbital holes lie ten pairs of larger meshes. All the meshes are filled up by very delicate arachnoidal network.

Dimensions.—Length of the shell 0.4 to 0.5, breadth 0.5 to 0.7; ring 0.06 to 0.08 long.

Habitat.—Central Pacific, Station 270, depth 2925 fathoms.

Suborder II. Botryodea, Haeckel, 1881 (Pl. 96).

Definition.—Nassellaria with a complete lattice-shell, exhibiting constantly a lobate and multilocular cephalis, with three to five or more separated lobes, and two to three or more constrictions.

The suborder Botryodea differs from the other Cyrtellaria in the multilocular and lobate shape of the cephalis, which is composed of at least three or four, often five or six, and sometimes even a greater number of lobes, which are separated by constrictions and partly also by internal septa. This characteristic shape is found neither in the Spyroidea (with bilocular cephalis) nor in the Cyrtoidea (with simple cephalis). The affinities of the former group to the two latter form a very complicated problem, which is not yet solved; the morphology of the Botryodea is the most difficult part in the system of Nassellaria, and what we can here give, are incomplete and unsatisfactory beginnings only.

Up to the year 1860 only a single genus of the Botryodea was known, Lithobotrys, one of the oldest genera of "Polycystina," and described by Ehrenberg in 1844 (Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 74). He gave the following definition:—"Loricæ siliceæ articuli in adulto non in seriem, sed in uvæ brevis formam, id est in loculos plus minus discretos nonnullos contiguos dispositi. Proxime ad Lithocampem accedit." In his first System (1847) Lithobotrys is placed with Lithocampe among his family Lithochytrina. Afterwards (1860) Ehrenberg added two new genera, under the names Botryocampe and Botryocyrtis and figured some species of these incompletely in his last works (1872, 1875).

In my Monograph I founded for these three genera the separate subfamily of Polycyrtida, added as a fourth genus Spyridobotrys, and gave to the group the following definition (1862, loc. cit., p. 341):—"Lattice-shell divided by two or more annular strictures, partly longitudinally, partly transversely, into three or more unequal chambers, which are placed in different planes and have a different relation to the poles of the shell-axis."

The new and remarkable forms of Botryodea, which I subsequently found in the Challenger collection, demonstrated that the Botryodea differ from the other Cyrtellaria (the Cyrtoidea as well as the Spyroidea) in a far higher degree than I formerly had supposed. A synopsis of the figures in Pl. 96 will give sufficient evidence of this view. Therefore in my Prodromus (1881, p. 439) I completely separated the Botryodea (or Botrida) from the other suborders of Cyrtellaria (Spyrida and Cyrtida).

Bütschli gave, in 1882, in his paper on the Cyrtida (loc. cit.) a very accurate description of Lithobotrys geminata, and pointed out its close affinity to Lithocorythium and Lithomelissa, and the importance of an oblique septum separating the cephalis into a smaller anterior and a larger posterior lobe. His views on the Botryodea (as a subordinate group of the Cyrtoidea) are however incomplete, since the peculiar forms, described in the following pages, were unknown to him.

According to the wide morphological divergence of the different Botryodea, and the numerous peculiar forms developed from it, we here divide the whole group into three families and ten genera, with fifty-five species. These form, however, only a small part of the large and varied mass of closely related forms which are found in the rich collections of the Challenger. The great difficulty of researches on their intimate structure, and the great amount of time required for it, prevented me from giving a more complete and exact description than the one here given. The observation of the small shells from all the different sides is a difficult task, requiring years of work, and its satisfactory explanation would be possible only by means of numerous figures.

The three families of Botryodea, here described, correspond to the three first groups of Cyrtoidea. The first family, Cannobotryida, corresponds to the Monocyrtida clausa and to the Zygospyrida; their shell consists of a cephalis only, without subsequent joints. The second family, Lithobotryida, corresponds to the Dicyrtida and Phormospyrida; their shell is composed of a cephalis and a thorax, both joints being separated by a transverse cortinar septum and a collar stricture. The third family, Pylobotryida, has a three-jointed shell, like the Tricyrtida, with cephalis, thorax and abdomen.

The cephalis is the most characteristic part of the shell of the Botryodea and its lobulate and multilocular shape separates them from the Spyroidea and Cyrtoidea. It represents the whole shell in the Cannobotryida, and in the young state of the two other families, which afterwards develop a thorax (Lithobotryida) and an abdomen (Pylobotryida). The typical lobulation of the cephalis is probably originally caused by internal septa; and these may be originated by branches of the internal columella, which corresponds either to the central ascending columella of the Plectoidea or to the excentric ascending dorsal rod of the sagittal ring of the Stephoidea. But afterwards, when the original septa disappear and are lost by reduction, only the external constrictions remain to indicate the limits of the single lobes.

Among the internal septa and the corresponding external constrictions which effect the lobulation of the cephalis, may be distinguished primary or constant septa and secondary or inconstant septa. As primary septa we regard firstly an oblique frontal septum and secondly a vertical sagittal septum. The frontal septum (described accurately by Bütschli) has usually two or three pairs of pores and ascends obliquely from the base to the anterior face of the cephalis, where it is inserted in the orbital region; it divides the cephalis into a smaller anterior or facial lobe and a larger posterior or occipital lobe. The latter is commonly higher and more developed than the former and partly covers its upper face, like the crest of a helmet. The facial lobe is again bisected by an incomplete sagittal septum and a corresponding partial constriction on the anterior face. We find, therefore, in this original cephalis of the Botryodea, three primary lobes, an odd larger occipital lobe and two paired smaller facial lobes. The typical trilobed cephalis may be regarded perhaps as the common original form of the Botryodea.

The secondary and inconstant constrictions which we find in many Botryodea, and which produce a greater number of lobes in the cephalis, require further accurate observation. The following cases of lobation may be considered as the most important:—(1) Cephalis with four lobes, opposite in two pairs (two larger occipital and two smaller facial lobes, separated by a complete sagittal and an oblique frontal constriction); (2) cephalis with four unequal lobes, two of which are odd and sagittal, two paired and lateral (the odd occipital lobe usually larger and the odd mandibular lobe smaller than the two paired lateral or buccal lobes); (3) cephalis with five lobes (a large odd occipital lobe and two pairs of smaller lobes, anterior nasal, and lateral buccal lobes); (4) cephalis with five lobes, three of which are odd (a posterior occipital, middle frontal, and anterior facial lobe), and one pair of lateral lobes; (5) cephalis with six lobes, opposite in pairs (two larger occipital, two smaller nasal and two intermediate lateral or buccal lobes); (6) cephalis with six lobes, two of which are odd and sagittal (a large occipital and a smaller nasal lobe), four opposite in pairs (two anterior and two posterior buccal lobes); (7) cephalis with seven lobes, three of which are odd (a large posterior occipital, a middle frontal, and an anterior small nasal lobe), four opposite in two pairs (an anterior buccal and a posterior temporal pair); (8) cephalis with eight lobes, two of which are odd (a large posterior occipital and a small anterior frontal lobe) and six opposite in three lateral pairs; (9) cephalis with nine lobes, three of which are odd (an occipital, a frontal and a nasal lobe) and six opposite in three lateral pairs; (10) cephalis with ten lobes, two of which are odd (a large occipital and a smaller frontal lobe) and the other eight opposite in pairs; (11) cephalis with numerous lobes (twelve to fifteen or more) which are symmetrically disposed on each side of the median plane; (12) cephalis with numerous lobes (twelve to fifteen or more) which are irregularly and sometimes spirally conglomerated.

All these different forms of lobation require a far more thorough examination than I can devote to them, and may furnish examples of regular laws of development. The irregular forms are rather common, and I have found some very irregular Botryodea (not here described) in which I could not determine the topographical regions of the cephalis. The difficulty in the examination of these complicated forms is increased by their very small size, which does not reach the usual dimensions of the other Cyrtellaria. In some cases I was able to observe on the base of the cephalis the same typical cortinar pores (in two or three pairs), which we also find in the same part of the cephalis in the Spyroidea and Cyrtoidea, and which are inherited from the Semantida.

The thorax of the Botryodea, or the second shell-joint, absent in the Cannobotryida, is usually of very simple form, ovate, truncate, conical or cylindrical, and consists of a secondary joint, developed from the base of the cephalis. The thorax is usually small, about the same size as the cephalis or a little larger, whilst in the Cyrtoidea it is commonly much larger than the latter. Its terminal mouth is closed by a lattice-plate in the Botryocellida, while it remains open in the Botryopylida and Pylobotryida.

The abdomen, or the third shell-joint, developed in the Pylobotryida only, generally also exhibits a very simple shape, like the thorax, and it is a tertiary joint developed from the base of the thorax. It exhibits to the latter the same relation as in the Tricyrtida. The terminal mouth of the abdomen remains open in the Botryocyrtida; it becomes closed by a lattice-plate in the Botryocampida.

The lattice-plate forming the shell of the Botryodea is usually very thin and fragile, with very small circular pores. These are often very numerous, at other times scarce, and sometimes nearly wanting, so that the shell appears hyaline. In this group there never occurs that great variety in form and size of the pores, which numerous Cyrtoidea and Spyroidea exhibit.

The radial apophyses which are found in the majority of Botryodea seem to correspond in position and relation to the typical radial beams of the other Nassellaria, viz., three descending basal feet arising from the base of the cephalis, and an ascending vertical apical horn arising from the top of the cephalis. Here also they seem to be inherited from the Plectoidea or Stephoidea (Cortina, Cortiniscus). But whilst these four typical radial beams in the other Nassellaria are usually simple spines or solid rods, here they usually appear as hollow cylindrical tubes, the thin wall of which is pierced by the same small pores as the shell. These porous tubes are either straight or slightly curved, often inflated and ovate at the base. We find in their number and disposition the same variety as in the simple radial spines of the other Nassellaria. The original number may here also be seen in the development of four typical beams, an ascending apical tube on the top of the cephalis, and three descending basal tubes on its base; the odd posterior tube of the latter corresponds to the caudal foot, the two paired anterior to the pectoral feet. There is often also a fourth foot developed opposite to the caudal, and representing a sternal tube. Sometimes also two superior tubes are developed, a posterior occipital and an anterior frontal. The different apophyses may be lost by reduction. I have never observed Botryodea with more than five apophyses.

The Central Capsule of the Botryodea is not yet sufficiently known, no living species having been observed. In some preparations from specimens in the Challenger collections, stained by Dr. John Murray with carmine immediately after the dredging operation, single Botryodea are to be found in which the central capsule is deeply coloured. In Botryopera quinqueloba (Pl. 96, fig. 2) it filled up the greater part of the cephalis and seemed to be divided into some small lobes. In Lithobotrys sphærothorax (Pl. 96, fig. 15) it was divided into four lobes, three of which filled the trilobed cephalis, the fourth large lobe occupying a great part of the spherical thorax. Details of their structure, unfortunately, were not recognisable. There can, however, be no doubt that they are the same as in all other Nassellaria.

Synopsis of the Families of Botryodea.

1. Shell monothalamous, consisting of the lobate cephalis only, 1. Cannobotryida.

2. Shell dithalamous, composed of a lobate cephalis and a simple thorax, 2. Lithobotryida.

3. Shell trithalamous, composed of a lobate cephalis, a thorax and an abdomen, 3. Pylobotryida.

Family LVI. Cannobotryida, Haeckel (sensu emendato).

Definition.—Botryodea monothalamia, the shell of which represents a lobate cephalis, without thorax and abdomen.

The family Cannobotryida (retained here with a stricter definition than originally was given in my Prodromus) comprises those Botryodea, in which the whole shell is represented by the cephalis alone, without thorax and abdomen. Since the two latter joints, found in the two following families, are secondary productions, the Cannobotryida must be regarded as the ancestral forms of all Botryodea, in an ontogenetic as well as in a phylogenetic sense.

Two species only of this family have been hitherto known, incompletely described by Ehrenberg as Lithobotrys triloba and Lithobotrys quadriloba. A great number of similar forms are to be found in the Radiolarian ooze of the Central Pacific, but they are very minute, and difficult to examine. We can describe here only twelve species of these, which we arrange in two genera; Botryopera without porous tubes, and Cannobotrys bearing a variable number of porous cylindrical tubes (one to five). The number of lobes of the cephalis is also variable in each genus (one to five or more). If in the future these minute and interesting shells should be better examined, it would be advisable to distinguish a number of genera according to the different number of the porous tubes and of the lobes of the cephalis. The base of the latter is constantly closed by a basal lattice-plate, and usually exhibits two or three pairs of cortinar pores, identical with those of the Semantida.

The phylogenetic origin of the Cannobotryida may be found either in the Zygospyrida or in the Monocyrtida; they differ from these two similar groups in the lobation of the cephalis, which is effected by the development of internal septa and external constrictions.

Synopsis of the Genera of Cannobotryida.

Cephalis without porous tubes, 486. Botryopera.

Cephalis with a variable number of porous tubes, 487. Cannobotrys.

Genus 486. Botryopera,^[104] n. gen.

Definition.—Cannobotryida without tubes on the cephalis.

The genus Botryopera is the simplest form among the Botryodea, the shell consisting of a lobate cephalis only, without tubes or radial appendages. It may be derived either from Dictyospyris or from Archicapsa by development of the horizontal fold in the frontal face of the shell, and the corresponding internal frontal septum, which separates the larger occipital lobe from the smaller facial half; the latter may be divided again into paired frontal lobes, lateral buccal lobes, &c. Botryopera may be the common ancestral form of many Botryodea.

1. Botryopera cyrtoloba, n. sp. (Pl. 96, fig. 1).

Cephalis trilobate; the posterior odd occipital lobe helmet-shaped, about twice as large as the two paired anterior frontal lobes, which are subovate and covered by the upper half of the former. Pores small and numerous, subregular, circular; some larger pores at the base.

Dimensions.—Length of the shell 0.08, basal breadth 0.06.

Habitat.—Central Pacific, Station 265 to 274, depth 2350 to 2925 fathoms.

2. Botryopera triloba, Haeckel.

Lithobotrys triloba, Ehrenberg, 1854, Mikrogeol., Taf. xxii. fig. 30.

Cephalis trilobate; the occipital lobe subcylindrical, one and a half times as long as the two frontal lobes, which are slender, ovate and not covered by the former. Pores small and numerous.

Dimensions.—Length of the shell 0.05, breadth 0.03.

Habitat.—Fossil in Tertiary rocks of the Mediterranean (Sicily, Greece, &c.)

3. Botryopera quadriloba, Haeckel.

Lithobotrys quadriloba, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 84.

Cephalis quadrilobate; the occipital lobe helmet-shaped, one and a half times as long as the two paired hemispherical buccal lobes, and twice as large as the anterior frontal lobe. Pores not numerous, rather large, circular.

Dimensions.—Length of the shell 0.06, breadth 0.04.

Habitat.—Fossil in Barbados and North America (Virginia).

4. Botryopera quinqueloba, n. sp. (Pl. 96, fig. 2).

Cephalis quinquelobate; the occipital lobe helmet-shaped, and twice as long as the two hemispherical frontal lobes, three times as long as the subspherical lateral buccal lobes. Pores scarce, small, circular.

Dimensions.—Length of the shell 0.07, basal breadth 0.05.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

5. Botryopera multiloba, n. sp.

Cephalis multilobate; the posterior odd occipital lobe ovate, and of about the same size as the anterior frontal half of the shell, which is clustered and divided into five to seven smaller lobes, an odd subspherical sternal lobe, and on each side of it two or three pairs of smaller subspherical lobes.

Dimensions.—Length of the shell 0.09, breadth 0.06.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

Genus 487. Cannobotrys,^[105] Haeckel, 1881, Prodromus p. 440.

Definition.—Cannobotryida with tubes on the cephalis.

The genus Cannobotrys differs from the preceding Botryopera in the development of hollow radial tubes, arising from the lobate cephalis in various numbers. According to their number the genus may be divided into various subgenera: (1) Cannobotrantha (monocanna) with a single apical tube; (2) Cannobotrella (dicanna) with two divergent tubes, an ascending apical and a descending sternal one; (3) Cannobotrissa (tricanna) with three tubes in the sagittal plane (an upper apical, a posterior caudal, and an anterior sternal); (4) Cannobotromma (tetracanna) with four radial tubes disposed like the four typical spines of Cortina (compare p. 950), and Cannobotrusa (pentacanna) with five radial tubes disposed like the five typical spines of Stephanium (p. 952). Perhaps these five groups may be separated as five genera, possessing near relations to five very different genera of Nassellaria (Circospyris, Halicapsa, Archibursa, Cortina, Stephanium, &c.)

1. Cannobotrys monocanna, n. sp.

Cephalis trilobate, with a single cylindrical straight apical tube on the apex of the occipital lobe, which is helmet-shaped, and about one and a half times as long as the two subspherical frontal lobes. Pores small and numerous, subregular, circular.

Dimensions.—Length of the shell 0.05, breadth 0.03.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

2. Cannobotrys dicanna, n. sp.

Cephalis quadrilobate, with two divergent tubes, an odd apical tube on the apex of the posterior occipital lobe, and an odd sternal tube on the anterior frontal lobe. Between these two odd lobes lie two paired lateral or buccal lobes, of about the same size. Shell nearly hyaline, with very few minute pores.

Dimensions.—Length of the shell 0.06, breadth 0.04.

Habitat.—Indian Ocean; Madagascar (Rabbe), surface.

3. Cannobotrys tricanna, n. sp. (Pl. 96, fig. 3).

Cephalis quinquelobate, with three curved cylindrical tubes in the sagittal plane; an ascending apical tube on the apex of the helmet-shaped occipital lobe, and two horizontal tubes on the base of the shell (a posterior caudal, c, and an anterior sternal, z). The two frontal lobes are hemispherical, and twice as large as the two lateral buccal lobes. Pores very small and numerous.

Dimensions.—Length of the shell 0.08, basal breadth 0.06.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

4. Cannobotrys sagittalis, n. sp.

Cephalis multilobate, with three straight divergent cylindrical tubes in the sagittal plane; a vertical apical tube on the apex of the ovate occipital lobe, and two horizontal tubes on the base, as in the preceding similar species; it differs from the latter in the greater number of lobes (seven or nine), the two frontal lobes being divided into two or four secondary lobules.

Dimensions.—Length of the shell 0.1, breadth 0.07.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

5. Cannobotrys cortina, n. sp. (Pl. 96, fig. 4).

Cephalis quinquelobate, with four cylindrical nearly straight tubes of equal size; an ascending, nearly vertical, apical tube on the apex of the occipital lobe, and three divergent descending tubes on the base of the shell (an odd posterior caudal tube and two paired anterior pectoral tubes). The two lateral buccal lobes are twice as large as the two anterior frontal lobes, and half as large as the posterior odd occipital lobe. The four tubes in this and the following species correspond probably to the four spines of Cortina (p. 950).

Dimensions.—Length of the shell 0.07, basal breadth 0.06.

Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 2925 fathoms.

6. Cannobotrys tetracanna, n. sp.

Cephalis multilobate, with four cylindrical curved tubes conical at their wider base, corresponding to those of the preceding species and to the four spines of Cortina. The odd occipital lobe is of about the same size as the anterior part of the shell, which is cleft into three pairs of roundish lobes, one pair of anterior larger frontal lobes, and two pairs of smaller lateral buccal lobes. Pores very few and minute.

Dimensions.—Length of the shell 0.11, basal breadth 0.07.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

7. Cannobotrys pentacanna, n. sp.

Cephalis quinquelobate, with five cylindrical slender curved tubes, three of which are placed in the sagittal plane (a superior apical, a posterior caudal, and an anterior sternal), whilst the other two are paired and diverge laterally (two pectoral tubes). The five tubes correspond exactly to the five typical spines of Stephanium (p. 952). The helmet-shaped occipital lobe of the shell is twice as large as each of the two anterior frontal lobes, and three times as large as each of the two lateral buccal lobes. Pores numerous.

Dimensions.—Length of the shell 0.07, basal breadth 0.04.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

Family LVII. Lithobotryida, n. fam.

Definition.—Botryodea dithalamia, the shell of which is composed of a lobate cephalis and a simple thorax, without abdomen.

The family Lithobotryida comprises those Botryodea in which the shell is divided by a transverse annular constriction into a lobate cephalis and a simple thorax. They correspond therefore to the Dicyrtida among the Cyrtoidea, and to the Phormospyrida among the Spyroidea. The thorax, or the second shell-joint, is in all these three families a secondary production, arising from the base of the cephalis; therefore the Lithobotryida must be phylogenetically derived from the Cannobotryida.

Several species of Lithobotrys were first described by Ehrenberg as Lithobotrys and Lithocorythium. These two genera are, however, identical, as has been demonstrated by Bütschli (1882, loc. cit., p. 519). Some other species united by Ehrenberg with Lithobotrys belong to other genera. The number of Lithobotryida found in the "Radiolarian ooze" of the Challenger collection, is far greater than that of the Cannobotryida and Pylobotryida. But only a small part of them could be thoroughly examined and described here, so that their number may be greatly augmented by further accurate researches. We here arrange those forms in four genera, representing two different subfamilies. The terminal mouth of the thorax remains open in the Botryopylida, whilst it becomes closed by a lattice-plate in the Botryocellida. In each group there are shells with and without porous tubes. The number of these tubes, and also the number of lobes of the cephalis, is very variable, and may in future serve for the distinction of more genera.

Synopsis of the Genera of Lithobotryida.

I. Subfamily Botryopylida. Mouth of the thorax open. Cephalis without porous tubes, 488. Botryopyle.

Cephalis with a variable number of porous tubes, 489. Acrobotrys.

II. Subfamily Botryocellida. Mouth of the thorax closed by a lattice-plate. Cephalis without porous tubes, 490. Botryocella.

Cephalis with a variable number of porous tubes, 491. Lithobotrys.

I. Subfamily Botryopylida. Mouth of the thorax open.

Cephalis without porous tubes,

488. Botryopyle.

Cephalis with a variable number of porous tubes,

489. Acrobotrys.

II. Subfamily Botryocellida. Mouth of the thorax closed by a lattice-plate.

Cephalis without porous tubes,

490. Botryocella.

Cephalis with a variable number of porous tubes,

491. Lithobotrys.

Genus 488. Botryopyle, Haeckel, 1881, Prodromus, p. 440.

Definition.—Lithobotryida without tubes on the cephalis, and with the mouth of the thorax open.

The genus Botryopyle comprises the simplest forms of Lithobotryida, the lobate cephalis bearing no tubes and the basal mouth of the thorax remaining open. It may be derived either from Dictyocephalus or from Desmospyris, by development of lobes on the cephalis and of an internal frontal septum, separating the larger occipital lobe from the smaller frontal half of the shell. The latter may be divided again into anterior frontal lobes, lateral buccal lobes, &c.

1. Botryopyle sethocorys, n. sp. (Pl. 96, fig. 7).

Cephalis trilobate, separated by a deep collar constriction from the hemispherical thorax, which is twice as broad. Occipital lobe helmet-shaped, little longer than the two hemispherical frontal lobes. Surface spiny. Pores irregular, roundish, of very different size.

Dimensions.—Length of the shell 0.1, breadth 0.07.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

2. Botryopyle cribrosa, Haeckel.

Lithobotrys cribrosa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 76, Taf. iii. fig. 20.

? Lithobotrys biceps, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 295, Taf. ix. fig. 23.

Cephalis trilobate, separated by a slight collar constriction from the ovate thorax, which is somewhat smaller. Occipital lobe very large, helmet-shaped, longer than the thorax and twice as long as the two subspherical frontal lobes. Pores regular, circular, scarce.

Dimensions.—Length of the shell 0.11, breadth 0.05.

Habitat.—Fossil in Barbados.

3. Botryopyle cephalodes, Haeckel.

Lithocorythium cephalodes, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. iv. fig. 6.

Cephalis quinquelobate, separated by a slight collar constriction from the larger conical thorax, which is gradually dilated towards the wide mouth. Occipital lobe helmet-shaped, little longer than the frontal half of the cephalis, which is divided into two pairs of lateral chambers, corresponding to the four crossed pores of the sagittal septum, figured by Ehrenberg. The figure of the latter is inverse, seen from the frontal face, a part of the frontal wall having been broken off.

Dimensions.—Length of the shell 0.08, breadth 0.05.

Habitat.—Fossil in Barbados.

4. Botryopyle dictyocephalus, n. sp. (Pl. 96, fig. 6).

Cephalis multilobate, separated by an oblique constriction from the subcylindrical thorax, which is somewhat larger and slightly curved. Occipital lobe conical, of the same length as the posterior part of the triangular frontal half of the shell, which is divided into five to seven lobes, two or three odd lobes in the median part, and one or two pairs of lateral lobes; very variable in size and form of the lobes. Mouth of the thorax wide, truncate.

Dimensions.—Length of the shell 0.12, breadth 0.07.

Habitat.—Central Pacific, Station 271 to 274, depth 2350 to 2750 fathoms.

5. Botryopyle inclusa, n. sp. (Pl. 96, fig. 5).

Cephalis multilobate, campanulate, separated by a sharp constriction from the inflated thorax, which is nearly twice as long and broad. Both joints of the shell are irregularly lobate, with numerous vaulted lobes of different sizes, and partly internal septa. Pores small and numerous.

Dimensions.—Length of the shell 0.1, breadth 0.06.

Habitat.—Mediterranean (Candia), Spratt, depth 1620 fathoms.

Genus 489. Acrobotrys, Haeckel,^[106] 1881, Prodromus, p. 440.

Definition.—Lithobotryida with tubes on the cephalis, and with the mouth of the thorax open.

The genus Acrobotrys differs from the preceding Botryopyle in the development of radial tubes, and from its probable ancestral form, Cannobotrys, in the development of a thorax, the basal mouth of which remains open. According to the varying number of the tubes we may distinguish the following five subgenera (corresponding to those of Cannobotrys), viz., (1) Acrobotrantha (monosolenia) with a single (apical) tube; (2) Acrobotrella (disolenia) with two divergent tubes (an apical and a sternal); (3) Acrobotrissa (trisolenia) with three sagittal tubes (an apical, a caudal, and a sternal); (4) Acrobotromma (tetrasolenia) with four tubes, like the four typical spines of Cortina; and (5) Acrobotrusa (pentasolenia) with five feet, corresponding to the five typical spines of Stephanium.

1. Acrobotrys monosolenia, n. sp.

Cephalis trilobate, with a single straight apical tube, which ascends vertically from the apex of the occipital lobe, and is pointed at the distal end, with an anterior oblique aperture. Two frontal lobes paired, ovate, half as long as the helmet-shaped occipital lobe. Thorax ovate, twice as long as the cephalis. Pores very scarce.

Dimensions.—Length of the shell 0.08, breadth 0.06.

Habitat.—Mediterranean (Corfu), surface.

2. Acrobotrys disolenia, n. sp. (Pl. 96, fig. 10).

Cephalis trilobate, with three odd ovate lobes of nearly equal size in the sagittal plane and two divergent straight slender cylindrical tubes, a vertical apical tube on the occipital lobe, and a horizontal nasal tube on the frontal lobe; the middle lobe between them is somewhat smaller. Thorax ovate, about twice as large as the cephalis, with constricted mouth. Pores small and numerous.

Dimensions.—Length of the shell 0.1, breadth 0.06.

Habitat.—Central Pacific, Station 265 to 274, depth 2350 to 2925 fathoms.

3. Acrobotrys aquaria, n. sp.

Cephalis quinquelobate, with two divergent long cylindrical curved tubes. Occipital lobe helmet-shaped, with an ascending apical tube; nasal lobe conical, with a descending sternal tube; between them a smaller odd middle lobe, and on each side of the latter an ovate frontal lobe. Thorax inflate, twice as long and broad as the cephalis. Pores small, scarce.

Dimensions.—Length of the shell 0.09, breadth 0.07.

Habitat.—South Pacific, Station 285, depth 2375 fathoms.

4. Acrobotrys acuminata, n. sp. (Pl. 96, fig. 9).

Cephalis sexlobate, with two divergent tubes. Occipital and frontal lobes ovate, odd; between them a cupola-shaped apical lobe, bearing an ascending pointed apical tube. On each side at the base a small buccal lobe, and between the paired buccal lobes an anterior nasal lobe with a descending curved sternal tube. Thorax smaller than the cephalis. Pores numerous and small.

Dimensions.—Length of the shell 0.11, breadth 0.09.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

5. Acrobotrys auriculata, n. sp. (Pl. 96, fig. 11).

Cephalis quadrilobate, with three pointed and auriculate tubes, two ascending apical (an anterior and a posterior) in the helmet-shaped occipital lobe, and a descending sternal tube on the base of the frontal lobe; between the lobes two lateral paired buccal lobes. Thorax campanulate, twice as broad as the cephalis. Pores rather large and numerous.

Dimensions.—Length of the shell 0.1, breadth 0.08.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

6. Acrobotrys trisolenia, n. sp. (Pl. 96, fig. 8).

Cephalis quadrilobate, with four odd lobes and three divergent curved tubes, an ascending apical tube in the conical occipital lobe, and two descending tubes on the anterior and posterior basal lobes; between these three lobes a small central lobe. Thorax ovate, about as large as the cephalis. Pores small and numerous.

Dimensions.—Length of the shell 0.11, breadth 0.05.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

7. Acrobotrys tetrasolenia, n. sp.

Cephalis trilobate, with four slender cylindrical tubes. Occipital lobe helmet-shaped, with an apical tube on the apex and a caudal tube on the base. Two frontal lobes ovate, prolonged into two paired pectoral tubes. The four tubes correspond in position to the four spines of Cortina. Thorax inflate, ovate, larger than the cephalis. Pores very scarce, rather large, irregular.

Dimensions.—Length of the shell 0.08, breadth 0.05.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

8. Acrobotrys pentasolenia, n. sp.

Cephalis quinquelobate, with five short conical tubes; three divergent odd tubes arise from three odd lobes; an apical from the occipital lobe, a posterior caudal from the suboccipital lobe, and an anterior sternal from the nasal lobe. Two paired lateral tubes arise from the base of two ovate frontal lobes. The five tubes correspond in disposition to the five spines of Stephanium. Thorax truncate. Pores small.

Dimensions.—Length of the shell 0.12, breadth 0.09.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

Genus 490. Botryocella,^[107] Haeckel, 1881, Prodromus, p. 440.

Definition.—Lithobotryida without tubes on the cephalis, and with the mouth of the thorax closed.

The genus Botryocella differs from the closely allied Botryopyle in having the mouth of the thorax closed, and may be derived from it by development of a lattice-plate, effecting this closure. It bears therefore the same relation to the latter that Dicolocapsa has to Dictyocephalus.

1. Botryocella nucula, Haeckel.

Lithobotrys nucula, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 76, Taf. iii. fig. 16.

Lithobotrys adspersa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 76, Taf. iii. fig. 15.

Cephalis trilobate; occipital lobe helmet-shaped, nearly twice as long as the two ovate frontal lobes. Thorax about as long as the cephalis. Pores very small and scarce.

Dimensions.—Length of the shell 0.06, breadth 0.03.

Habitat.—Fossil in Barbados.

2. Botryocella borealis, Haeckel.

Lithobotrys borealis, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 294, Taf. ii. fig. 3.

Cephalis trilobate; occipital lobe ovate, little longer than the two ovate frontal lobes. Thorax about twice as long as the cephalis. Pores very numerous and small.

Dimensions.—Length of the shell 0.08, breadth 0.04.

Habitat.—North Atlantic, Greenland, depth 1000 to 2000 fathoms.

3. Botryocella tricellaris, n. sp.

Cephalis trilobate, with three odd sagittal lobes; the middle or central lobe larger than the anterior frontal and smaller than the posterior occipital lobe. Thorax nearly spherical, about as long as the cephalis. Pores small and scarce.

Dimensions.—Length of the shell 0.08, breadth 0.06.

Habitat.—North Atlantic, Station 353, depth 2965 fathoms.

4. Botryocella quadricellaris, n. sp. (Pl. 96, fig. 13).

Cephalis quadrilobate; the helmet-shaped occipital lobe twice as long as the two paired subspherical buccal lobes, and three times as long as the odd spherical frontal lobe. Thorax nearly spherical, about as long as the cephalis.

Dimensions.—Length of the shell 0.1, breadth 0.05.

Habitat.—Central Pacific, Station 272, depth 4475 fathoms.

5. Botryocella quadrigemina, n. sp. (Pl. 96, fig. 14).

Cephalis quadrilobate, with two pairs of lateral ovate lobes and complete sagittal constriction; the two occipital lobes nearly twice as large as the two frontal lobes. Thorax ovate, separated from the cephalis by a collar septum with four cortinar pores (fig. 14).

Dimensions.—Length of the shell 0.09, breadth 0.06.

Habitat.—Indian Ocean, Sunda Strait (Rabbe), surface.

6. Botryocella multicellaris, n. sp. (Pl. 96, fig. 12).

Cephalis multilobate; occipital lobe helmet-shaped, very large, about twice as long and broad as the frontal half of the shell, which is divided into six to eight small roundish clustered lobes. Thorax subspherical, of about the same size as the cephalis.

Dimensions.—Length of the shell 0.1, breadth 0.05.

Habitat.—South Pacific Station 297, depth 1775 fathoms.

Genus 491. Lithobotrys,^[108] Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 74.

Definition.—Lithobotryida with tubes on the cephalis, and with the mouth of the thorax closed.

The genus Lithobotrys, the oldest and first known of the Botryodea, was founded by Ehrenberg in 1844, and was one of his five oldest genera of Polycystina. It represented by itself the suborder Botryodea until the year 1860. The numerous species described by Ehrenberg belong to very different genera of Botryodea, and partly also of Spyroidea. Following Bütschli (1882) we retain here the name Lithobotrys for those species, the type of which is Lithobotrys geminata. The genus Lithocorythium of Ehrenberg is for the greater part identical with it. When in the preceding genus Acrobotrys the mouth of the thorax becomes closed by lattice work, Lithobotrys arises. In the latter as well as in the former the number of tubes on the cephalis is different, and may characterise different subgenera.

1. Lithobotrys geminata, Ehrenberg.

Lithobotrys geminata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 76, Taf. iii. fig. 19.

Lithobotrys geminata, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi, p. 519, Taf. xxxiii. fig. 27, a to c.

? Lithocorythium platylophus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. iv. fig. 5.

Cephalis trilobate, with a single apical tube in the apex of the helmet-shaped occipital lobe, which is one and a half times as long as the two subspherical frontal lobes. Thorax ovate, one and a half times as long as the cephalis, with few small pores in six to eight transverse rows.

Dimensions.—Length of the shell 0.1, breadth 0.05.

Habitat.—Fossil in Barbados.

2. Lithobotrys lithocorythium, Haeckel.

Lithocorythium oxylophus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. iv. figs. 3, 4.

? Lithopera oxystauros, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. iii. fig. 6.

Cephalis trilobate, with a single apical horn or a pointed tube in the apex of the helmet-shaped occipital lobe, which is a little longer than the two ovate frontal lobes. Thorax ovate, about as long as the cephalis, with very numerous and small pores.

Dimensions.—Length of the shell 0.08, breadth 0.04.

Habitat.—Fossil in Barbados.

3. Lithobotrys nasuta, Ehrenberg.

Lithobotrys nasuta, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 76, Taf. iii. fig. 21.

Cephalis quadrilobate, with a single descending sternal or nasal tube on the base of the anterior or frontal lobe, which is half as long as the helmet-shaped occipital lobe and twice as large as the two lateral buccal lobes. Thorax ovate, twice as long as the cephalis. Pores rather large, circular.

Dimensions.—Length of the shell 0.11, broad 0.05.

Habitat.—Fossil in Barbados.

4. Lithobotrys ornata, Ehrenberg.

Lithobotrys ornata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 76, Taf. iii. fig. 18.

Cephalis quinquelobate, with two divergent ascending tubes, a posterior occipital and an anterior sternal or nasal tube. Occipital lobe campanulate, twice as large as the two frontal, and four times as large as the two buccal lobes. Thorax ovate, twice as long as the cephalis. Pores scarce and small. The specimen figured by Ehrenberg is very incomplete.

Dimensions.—Length of the shell 0.09, breadth 0.05.

Habitat.—Fossil in Barbados.

5. Lithobotrys sphærothorax, n. sp. (Pl. 96, fig. 15).

Cephalis trilobate, with two divergent cylindrical tubes, an ascending apical tube in the apex of the ovate occipital lobe, and a descending sternal or nasal tube in the campanulate frontal lobe; between the two lobes a smaller central lobe. Thorax spherical, twice as long as the latter. Pores very small, numerous.

Dimensions.—Length of the shell 0.08, breadth 0.06.

Habitat.—Western Tropical Pacific, Station 225, depth 4575 fathoms.

6. Lithobotrys mascula, n. sp. (Pl. 96, fig. 16).

Cephalis sexlobate, with two divergent cylindrical tubes, an ascending apical tube in the apex of the helmet-shaped occipital lobe and a descending sternal tube on the base, between the two kidney-shaped frontal lobes. The latter are half as large as the odd occipital lobe and of about the same size as the two inflated lateral buccal lobes, which are separated by a small odd nasal lobe.

Dimensions.—Length of the shell 0.13, breadth 0.08.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

7. Lithobotrys orchidea, n. sp. (Pl. 96, fig. 17).

Cephalis sexlobate, similar to the preceding species, but with five divergent and curved cylindrical tubes, which correspond to the five spines of Stephanium; an apical tube on the apex of the occipital lobe, a caudal tube on its base, a sternal tube between the two frontal lobes, and two paired pectoral tubes between the latter and the lateral buccal lobes. Pores small and scarce.

Dimensions.—Length of the shell 0.12, breadth 0.06.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Family LVIII. Pylobotryida, Haeckel (sensu emendato).

Definition.—Botryodea trithalamia, the shell of which is composed of a lobate cephalis, a thorax, and an abdomen.

The family Pylobotryida comprises those Botryodea in which the shell exhibits two parallel transverse annular constrictions, and is divided by these into three successive joints, corresponding to the cephalis, the thorax, and the abdomen of the Tricyrtida. As in the latter, the abdomen is here also a later production, arising from the terminal mouth of the thorax; therefore the Pylobotryida must be derived phylogenetically from the Lithobotryida.

Two genera of Pylobotryida were incompletely described in 1860 by Ehrenberg, Botryocyrtis and Botryocampe. We retain them here, with a stricter definition, however. Two other genera were added in my Prodromus—Pylobotrys and Phormobotrys. The small number of species here enumerated may be easily increased, since numerous forms, belonging probably to this family, are not sufficiently known. Their study is, however, very difficult and requires accurate examination of the tiny shells from different sides.

The four genera of Pylobotryida, here described, represent two different subfamilies. The terminal mouth of the abdomen remains open in the Botryocyrtida, whilst it becomes closed by a lattice-plate in the Botryocampida. There are in both groups shells with and without porous tubes; the number of these tubes, and also the number and disposition of the lobes in the cephalis, exhibits remarkable differences in the different species of those genera, and may in future serve for their division into a greater number of genera.

Synopsis of the Genera of Pylobotryida.

I. Subfamily Botryocyrtida. Mouth of the abdomen open. Cephalis without porous tubes, 492. Botryocyrtis.

Cephalis with a variable number of porous tubes, 493. Pylobotrys.

II. Subfamily Botryocampida. Mouth of the abdomen closed by a lattice-plate. Cephalis without porous tubes, 494. Botryocampe.

Cephalis with a variable number of porous tubes, 495. Phormobotrys.

I. Subfamily Botryocyrtida. Mouth of the abdomen open.

Cephalis without porous tubes,

492. Botryocyrtis.

Cephalis with a variable number of porous tubes,

493. Pylobotrys.

II. Subfamily Botryocampida. Mouth of the abdomen closed by a lattice-plate.

Cephalis without porous tubes,

494. Botryocampe.

Cephalis with a variable number of porous tubes,

495. Phormobotrys.

Genus 492. Botryocyrtis,^[109] Ehrenberg, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 829.

Definition.—Pylobotryida without tubes on the cephalis, and with the mouth of the abdomen open.

The genus Botryocyrtis, founded by Ehrenberg upon two Indian species, is the simplest among the Pylobotryida. It may have been derived from Botryopyle by the development of an abdomen (or a third shell-joint), the mouth of which remains open.

1. Botryocyrtis serpentis, Ehrenberg.

Botryocyrtis serpentis, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf. x. fig. 21.

Cephalis quadrilobate; the odd frontal and the two paired buccal lobes subspherical, about half as large as the odd occipital lobe. Thorax inflated, about as long as the cephalis and half as long as the ovate abdomen. Mouth of the latter constricted, of half the breadth.

Dimensions.—Length of the shell 0.12, breadth 0.06.

Habitat.—Indian Ocean (Zanzibar), depth 2200 fathoms, Pullen.

2. Botryocyrtis theocampe, n. sp. (Pl. 96, fig. 19).

Cephalis quadrilobate; the odd frontal and the two paired buccal lobes hemispherical, about half as large as the helmet-shaped occipital lobe. Thorax cylindrical, of equal length and breadth, one and a half times as broad as the cephalis and as the cylindrical abdomen. Pores rather large, irregular, roundish.

Dimensions.—Length of the shell 0.12, breadth 0.06.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

3. Botryocyrtis cerebellum, n. sp. (Pl. 96, fig. 18).

Cephalis quinquelobate; the odd frontal and the two paired buccal lobes ovate, about half as large as the two helmet-shaped paired occipital lobes (?). Thorax campanulate, twice as broad and long as the cephalis and as the truncate cylindrical abdomen.

Dimensions.—Length of the shell 0.12, breadth 0.08.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

4. Botryocyrtis quinaria, Ehrenberg.

Botryocyrtis quinaria, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf. x. fig. 16.

Cephalis quinquelobate; the odd occipital lobe ovate, twice as large as each of the other four subspherical lobes, the two anterior (or frontal) of which are somewhat smaller than the two posterior (or buccal). Thorax campanulate, somewhat larger than the truncate abdomen. Pores rather large, irregular.

Dimensions.—Length of the shell 0.09, breadth 0.05.

Habitat.—Indian Ocean (Zanzibar and Madagascar), surface.

Genus 493. Pylobotrys,^[110] Haeckel, 1881, Prodromus, p. 440.

Definition.—Pylobotryida with tubes on the cephalis, and with the mouth of the abdomen open.

The genus Pylobotrys differs from the closely allied Acrobotrys, its ancestral form, in the development of an abdomen or a third shell-joint, the basal mouth of which remains open.

1. Pylobotrys putealis, n. sp. (Pl. 96, fig. 21).

Cephalis multilobate, with a single curved and descending tube on the base of its anterior part (sternal tube). Occipital half of the cephalis divided into three large odd lobes (the largest the apical); facial half divided into three to five lobes, an odd frontal and one or two lateral pairs of small buccal lobes. Thorax truncate conical, about as large as the cephalis and larger than the truncate abdomen. Pores regular circular.

Dimensions.—Length of the shell 0.12, breadth 0.08.

Habitat.—Tropical Atlantic Station 347, depth 2250 fathoms.

2. Pylobotrys fontinalis, n. sp. (Pl. 96, fig. 20).

Cephalis trilobate, with three ovate lobes in the sagittal plane, of nearly equal size, and two divergent cylindrical tubes conical at the base. An ascending apical tube on the apex of the occipital lobe and a descending sternal tube on the base of the frontal lobe. The middle lobe between the former distinctly exhibits in the apical view (fig. 20) the collar septum with the four cortinar pores. Thorax campanulate, larger than the cephalis and the truncate abdomen.

Dimensions.—Length of the shell 0.11, breadth 0.06.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

3. Pylobotrys cerebralis, n. sp. (Pl. 96, fig. 22).

Cephalis multilobate, with four divergent cylindrical tubes, which are cylindrical, obliquely truncate at the mouth, and correspond in position to the four typical spines of Cortina; an ascending apical tube and three descending basal tubes (an odd caudal and two paired pectoral). The helmet-shaped occipital lobe is about as large as the frontal half of the cephalis, which is divided into three pairs of smaller pyriform lobes. Thorax subspherical, about as large as the cephalis and half as large as the inflated abdomen. Pores very scarce and small.

Dimensions.—Length of the shell 0.15, breadth 0.08.

Habitat.—Indian Ocean, Cocos Islands, Rabbe, surface.

Genus 494. Botryocampe,^[111] Ehrenberg, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 829.

Definition.—Pylobotryida without tubes on the cephalis, and with the mouth of the abdomen closed.

The genus Botryocampe may be derived from Botryocyrtis by development of a basal lattice-plate, closing the terminal mouth of the abdomen. It is at the same time closely allied to the Tricyrtid Theocapsa, and may be perhaps derived from this by lobation of the cephalis.

1. Botryocampe inflata, Ehrenberg.

Botryocampe inflata, Ehrenberg, 1861, Monatsber. d. k. Akad. d. Wiss. Berlin, p. 296; Abhandl. d. k. Akad. d. Wiss. Berlin, 1872, p. 285, Taf. ii. fig. 4.

Botryocampe inflata, Haeckel, 1862, Monogr. d. Radiol., p. 345.

Lithobotrys inflata, Bailey, 1856, Amer. Journ. Sci. and Arts, vol. xxii. p. 1, pl. i. fig. 15.

Cephalis trilobate, inflated, of about the same breadth and length as the tun-shaped thorax and the hemispherical abdomen. Frontal lobes of the cephalis ovate, a little smaller than the ovate odd occipital lobe. Pores numerous and small.

Dimensions.—Length of the shell 0.05 to 0.08, breadth 0.02 to 0.04.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Pacific, Stations 267 to 274, 241, 354, &c., surface, and in various depths.

2. Botryocampe theocapsa, n. sp.

Cephalis trilobate, half as long as the campanulate thorax, and one-third as long as the ovate abdomen. Frontal lobes subspherical, scarcely half as long as the helmet-shaped occipital lobe. Pores very small and scarce.

Dimensions.—Length of the shell 0.12, breadth 0.04.

Habitat.—South Atlantic, Station 335, depth 1425 fathoms.

3. Botryocampe galea, Haeckel.

Lithobotrys galea, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 83.

Lithocorythium galea, Ehrenberg, 1854, Mikrogeol., Taf. xxii. fig. 29, a, b.

Lithocorythium galea, Haeckel, 1862, Monogr. d. Radiol., p. 330.

Cephalis quinquelobate, about as large as the ovate thorax, and twice as large as the hemispherical abdomen (which is identical with the "crista obtusa finis anterioris" of Ehrenberg). Occipital lobe helmet-shaped, about twice as long as the two pairs of lateral lobes (the superior frontal and the inferior buccal lobes).

Dimensions.—Length of the shell 0.08, breadth 0.04.

Habitat.—Fossil in Barbados.

4. Botryocampe rotalia, n. sp. (Pl. 96, fig. 23).

Cephalis quinquelobate, half as large as the campanulate thorax and the subspherical abdomen. Occipital lobe ovate, one and a half times as long as the two ovate frontal lobes, and three times as long as the two subspherical buccal lobes. Collar septum with six distinct cortinar pores (two anterior jugular, two middle cardinal and two posterior cervical, fig. 23).

Dimensions.—Length of the shell 0.1, breadth 0.06.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

5. Botryocampe camerata, n. sp. (Pl. 96, fig. 24).

Cephalis multilobate, about as long and half as broad as the irregularly campanulate thorax, which is half as long as the subspherical large abdomen. Occipital lobe of the cephalis helmet-shaped, larger than its uviform frontal part, which is divided into six to eight small subspherical lobes. In the interior of the thorax and abdomen irregularly branched rods are visible, which divide their inner space into compartments or incomplete chambers. Pores large, regular, circular, hexagonally framed.

Dimensions.—Length of the shell 0.15, breadth 0.09.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Genus 495. Phormobotrys,^[112] Haeckel, 1881, Prodromus, p. 440.

Definition.—Pylobotryida with tubes on the cephalis, and with the mouth of the abdomen closed.

The genus Phormobotrys differs from the similar and closely allied Pylobotrys in the development of a basal lattice-plate closing the terminal mouth of the thorax, and corresponds therefore to Lithobotrys among the Lithobotryida. As in the latter and in Cannobotrys, &c., so here in Phormobotrys, different subgenera may be distinguished, according to the different number and disposition of the radial tubes which become developed from the lobate cephalis.

1. Phormobotrys trithalamia, n. sp. (Pl. 96, fig. 26).

Cephalis trilobate, with a single apical tube, which is only one-third as long, spindle-shaped, pointed, with frontal opening. Frontal lobes ovate, two-thirds as long as the helmet-shaped occipital lobe. Internal frontal septum of the cephalis with four large pores. Thorax cylindrical, twice as long as the hemispherical abdomen. Pores small and numerous, irregular, roundish.

Dimensions.—Length of the shell 0.16, breadth 0.05.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

2. Phormobotrys pentathalamia, n. sp. (Pl. 96, fig. 27).

Cephalis quinquelobate, with a single conical apical tube of the same length, which has an obliquely truncate frontal opening. Odd frontal and paired buccal lobes smaller than the sternal and the occipital lobe. Internal frontal septum with six large pores. Thorax inflated, a little larger than the subspherical abdomen. Pores subregular, circular.

Dimensions.—Length of the shell 0.15, breadth 0.08.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

3. Phormobotrys hexathalamia, Haeckel.

Botryocampe hexathalamia, Haeckel, 1862, Monogr. d. Radiol., p. 344, Taf. xii. fig. 10.

Cephalis sexlobate, with a single apical horn, which is solid, vertical, cylindrical, pointed, only one-third as long. Frontal lobes subcylindrical, nearly as long as the kidney-shaped occipital lobe, three to four times as long as the small buccal lobes and the odd sternal lobe. Thorax tun-shaped, smaller than the cephalis, larger than the hemispherical abdomen. Pores numerous, subregular, circular.

Dimensions.—Length of the shell 0.13 to 0.15, breadth 0.05 to 0.06.

Habitat.—Mediterranean, Messina, surface.

4. Phormobotrys cannothalamia, n. sp. (Pl. 96, fig. 25).

Cephalis trilobate, of about the same breadth and length as the campanulate thorax, which is three times as long as the flat cap-shaped abdomen. The middle (or central) lobe of the cephalis is simple, nearly cubical, and smaller than the ovate occipital and frontal lobe. The two latter are prolonged into two slender cylindrical divergent tubes. Pores small and very numerous.

Dimensions.—Length of the shell 0.1, breadth 0.05.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

5. Phormobotrys polythalamia, n. sp.

Cephalis multilobate, of the same length and breadth as the subspherical thorax, and half as long as the ovate abdomen. Occipital lobe helmet-shaped, about as large as the frontal half of the cephalis, which is divided into six to eight lobes (two odd and two or three pairs of lateral lobes). Four cylindrical tubes corresponding to the four typical spines of Cortina, an ascending apical and three descending basal tubes (a posterior caudal and two anterior pectoral).

Dimensions.—Length of the shell 0.14, breadth 0.08.

Habitat.—South Pacific, Station 298, depth 2225 fathoms.

Suborder III. CYRTOIDEA, Haeckel, 1862.

Definition.—Nassellaria with a complete lattice-shell, exhibiting a simple or reduced cephalis, which is neither bilocular nor lobate, without sagittal constriction.

The order Cyrtoidea, described by me in 1862 as the family Cyrtida, is by far the largest of all the main groups of Radiolaria, and remarkable from the extraordinary variety of forms and the number of species. In the following system more than eleven hundred species are described, comprising about one-fourth of the number of species in the whole class of Radiolaria. This astonishing variety, however, is not effected by development of a large number of different types, but by an extraordinary variability within certain restricted boundaries, similar to what is seen among insects and birds. The number of genera, therefore, is comparatively small, and they may all be disposed into four families only, which in my Monograph (1862, p. 280) were distinguished as Monocyrtida, Dicyrtida, Tricyrtida and Stichocyrtida. If we divide these four groups in the following pages into twelve families and twenty-four subfamilies, we are guided by practical considerations only, hoping thereby to give a better survey of the difficult labyrinth of Cyrtoidean morphology.

The Cyrtoidea are characterised by this wonderful richness of specific forms not only in the present seas, but also for millions of years in the former ages of our globe. The majority of all the fossil Radiolaria which are now known belong to this group, and many species of it are so common that great rocks are formed by their union. The fact was first observed by Ehrenberg, who in his first system of Polycystina (1847, loc. cit., p. 54) enumerated forty-four genera and two hundred and eighty-two species; the Cyrtoidea, his Polycystina solitaria, form the preponderant majority of the whole class, viz., twenty-five genera and one hundred and ninety-three species.

In this first system (of 1847), as well as in the last systematic table of Ehrenberg (of 1875, loc. cit.), the Cyrtida as "Polycystina solitaria" are opposed to all other Radiolaria, as "Polycystina composita." The former bear the definition "Testæ siliceæ spatio interno ample pervio, aut passim levius transverse constricto"; the latter, however, "Testæ siliceæ spatio interno celluloso aut strictura longitudinali constricto." In reality these definitions are insufficient, and the conclusions which Ehrenberg derived from the organisation of the Polycystina solitaria and composita, were quite erroneous. So also are the definitions of the three families into which he divided the Polycystina solitaria, afterwards (in 1875) called by him "Monodictya nassellaria." These three families were the Halicalyptrina, Lithochytrina and Eucyrtidina. With these were also united the three genera of Botryodea known to Ehrenberg (Lithobotrys, Botryocampe, Botryocyrtis). We entirely separate these here from the true Cyrtida, on account of their lobate or multilocular cephalis.

Whilst Ehrenberg only knew the skeleton of the Polycystina solitaria, the first observations of living Cyrtida were published by Johannes Müller, 1858, in his fundamental treatise. He gave the first description and figures of the central capsule of this group, with the characteristic lobes developed from its basal part; and of the pseudopodia radiating on all sides (loc. cit., Taf. vi.). The forms described by him were all Mediterranean, one Dicyrtid (Lithomelissa mediterranea), two Tricyrtids (Eucyrtidium zancleum and Pterocanium charybdeum), and one Stichocyrtid (Lithocampe tropeziana).

In my monograph (1862, p. 272-341) I gave a detailed description of all known and some new Cyrtida, and characterised this family by the fundamental monaxonial form of the shell, with two different poles (an upper apical and a lower basal pole), and by the unipolar growth, beginning from the apical pole. I pointed out also the peculiar structure of the monaxonial central capsule. At that time I divided the Cyrtida into five subfamilies, in which, however, the Spyroidea (= Zygocyrtida), and the Botryodea (= Polycyrtida) were united with the true Cyrtoidea (Monocyrtida, Dicyrtida, Stichocyrtida).

The astonishing number of new and interesting forms of Cyrtida which I found in the rich collection of the Challenger (beginning from 1876), and mainly in the Radiolarian ooze of the Central Pacific (Stations 263 to 274), enabled me to give in my Prodromus, in 1881, a greatly enlarged and amended system of this important group. I separated there the Spyroidea (= Zygocyrtida), and the Botryodea (= Polycyrtida) from the true Cyrtoidea by restricted definition, pointing out the essential differences in the structure of the cephalis in these groups of Cyrtellaria. The latter name, as here used, is therefore identical with the "Cyrtida" of my Monograph. In the Prodromus I divided the true Cyrtida (p. 426) into five subfamilies and thirty tribes, corresponding to the differences in the number of the shell-joints and of the radial apophyses, and in the shape of the closed or open mouth. These groups are here retained, but reduced to four families and twenty-four subfamilies, since the Tetracyrtida are better united with the Stichocyrtida (compare below).

Richard Hertwig in his work Organismus der Radiolarien (1879, pp. 74 to 86) gave the first accurate description of the finer structure of the central capsule of the Cyrtida, and pointed out their character as true Monopylea, with porochora and podoconus, and the peculiar shape of its nucleus. He also published excellent figures of some interesting new species.

O. Bütschli, 1882, in his valuable paper entitled: "Beiträge zur Kentniss der Radiolarien-Skelette, insbesondere der der Cyrtida" (Zeitschr. für wiss. Zool., vol. xxxvi. p. 485) made an attempt at a natural classification of the Cyrtida, which he derived from the Spyroidea or Zygocyrtida. As already mentioned above, we cannot accept this essay as the foundation of a true natural system, since the affinities of the Cyrtellaria (and of the Nassellaria as a whole) are far more complicated and difficult than Bütschli supposed. His views were supported by accurate observations only on the structure of the fossil Cyrtoidea of Barbados; these, however, represent the minority only of the genera, and many interesting and important forms (mainly of true "Monocyrtida") remained unknown to Bütschli. A great part, however, of his observations are very useful, and his remarks on comparative morphology are very suggestive.

The Cyrtoidea may be divided into families and subfamilies according to three different principles, viz., (1) the number of joints into which the shell is divided by transverse strictures; (2) the number of radial apophyses which arise from the shell; (3) the shape of the basal mouth, which is either open or closed by a lattice-plate. At present every attempt of classification in this large group must be more or less artificial, since the affinities of the numerous smaller and larger groups are extremely complicated, and the ontogeny, the only sure guide in this phylogenetical labyrinth, is perfectly unknown. It seems therefore the most convenient to employ for our artificial classification, first, the number of shell-joints, second, the radial structure, and third, the shape of the mouth.

A. The number of joints into which the shell is divided by transverse constrictions, serves here for the distinction of four primary groups or suborders of the Cyrtoidea, viz., (1) Monocyrtida with one joint; (2) Dicyrtida with two joints; (3) Tricyrtida with three joints; and (4) Stichocyrtida with four or more joints. In my Prodromus (1881, p. 426) I divided the latter group into Tetracyrtida (with four joints), and Stichocyrtida (with five or more joints); but these two groups may be united, since the fourth and all the succeeding joints are of rather indifferent shape and of little morphological value. The three first joints, however, are usually very different and possess a high morphological importance, so that we distinguish the first joint as cephalis, the second as thorax, and the third as abdomen. The uppermost transverse constriction, which separates the two first joints, cephalis and thorax, is the collar stricture and is usually caused by an internal fenestrated septum, the cortinar septum. The second constriction, which separates the second and third joints (thorax and abdomen) is called the lumbar constriction. The following constrictions (in the Stichocyrtida) are indifferent and of little morphological interest, and require therefore no peculiar designation.

B. The radial structure, indicated by radial apophyses arising from the shell, offers three principal differences, according to which the whole group of Cyrtoidea may be divided into three large groups or sections, viz., (1) Pilocyrtida, or Cyrtoidea triradiata, with three radial apophyses; (2) Astrocyrtida, or Cyrtoidea multiradiata, with numerous radial apophyses (four to nine or more); and (3) Corocyrtida, or Cyrtoidea eradiata, without external radial apophyses. The majority of Cyrtoidea are Pilocyrtida, with three radial apophyses, which are probably homologous to the three primary feet of the Plectoidea and of Cortina (therefore "cortinar feet"). The Astrocyrtida, or the Cyrtoidea with a variable number of radial apophyses (at least four to six) may be derived from the Pilocyrtida by interpolation of secondary or interradial apophyses between the three primary or perradial apophyses. The Corocyrtida, however, or the Cyrtoidea without external radial apophyses, may have originated by reduction and loss of the latter, either from the Pilocyrtida or from the Astrocyrtida.

C. The shape of the basal mouth in the Cyrtoidea exhibits two essential differences only, viz., (1) the terminal mouth of the shell is a simple wide opening in the Stomocyrtida, or (2) the terminal mouth is closed by a lattice-plate, in the Clistocyrtida. As these two different cases occur in all the twelve families, which we have distinguished according to the differences in the number of joints and in the radial structure, we get altogether twenty-four subfamilies which are synoptically arranged in the following table:—

Synopsis of the four sections, twelve families and twenty-four subfamilies of CYRTOIDEA. PILOCYRTIDA. Cyrtoidea triradiata. (Three radial apophyses.) ASTROCYRTIDA. Cyrtoidea multiradiata. (Four to nine or more apophyses.) COROCYRTIDA. Cyrtoidea eradiata. (No radial apophyses.)

Mouth of the shell. Aperta. Clausa. Aperta. Clausa. Aperta. Clausa.

MONOCYRTIDA. (Cyrtoidea monothalamia). Tripocalpida. Phænocalpida. Cyrtocalpida.

Archipilida. Archiperida. Archiphormida. Archiphænida. Archicorida. Archicapsida.

DICYRTIDA. (Cyrtoidea dithalamia). Tripocyrtida. Anthocyrtida. Sethocyrtida.

Sethopilida. Sethoperida. Sethophormida. Sethophænida. Sethocorida. Sethocapsida.

TRICYRTIDA. (Cyrtoidea trithalamia). Podocyrtida. Phormocyrtida. Theocyrtida.

Theopilida. Theoperida. Theophormida. Theophænida. Theocorida. Theocapsida.

STICHOCYRTIDA. (Cyrtoidea polythalamia). Podocampida. Phormocampida. Lithocampida.

Stichopilida. Stichoperida. Stichophormida. Stichophænida. Stichocorida. Stichocapsida.

Synopsis of the four sections, twelve families and twenty-four subfamilies of CYRTOIDEA. PILOCYRTIDA. Cyrtoidea triradiata. (Three radial apophyses.)

Mouth of the shell. Aperta. Clausa.

MONOCYRTIDA. (Cyrtoidea monothalamia). Tripocalpida.

Archipilida. Archiperida.

DICYRTIDA. (Cyrtoidea dithalamia). Tripocyrtida.

Sethopilida. Sethoperida.

TRICYRTIDA. (Cyrtoidea trithalamia). Podocyrtida.

Theopilida. Theoperida.

STICHOCYRTIDA. (Cyrtoidea polythalamia). Podocampida.

Stichopilida. Stichoperida.

ASTROCYRTIDA. Cyrtoidea multiradiata. (Four to nine or more apophyses.)

Mouth of the shell. Aperta. Clausa.

MONOCYRTIDA. (Cyrtoidea monothalamia). Phænocalpida.

Archiphormida. Archiphænida.

DICYRTIDA. (Cyrtoidea dithalamia). Anthocyrtida.

Sethophormida. Sethophænida.

TRICYRTIDA. (Cyrtoidea trithalamia). Phormocyrtida.

Theophormida. Theophænida.

STICHOCYRTIDA. (Cyrtoidea polythalamia). Phormocampida.

Stichophormida. Stichophænida.

COROCYRTIDA. Cyrtoidea eradiata. (No radial apophyses.)

Mouth of the shell. Aperta. Clausa.

MONOCYRTIDA. (Cyrtoidea monothalamia). Cyrtocalpida.

Archicorida. Archicapsida.

DICYRTIDA. (Cyrtoidea dithalamia). Sethocyrtida.

Sethocorida. Sethocapsida.

TRICYRTIDA. (Cyrtoidea trithalamia). Theocyrtida.

Theocorida. Theocapsida.

STICHOCYRTIDA. (Cyrtoidea polythalamia). Lithocampida.

Stichocorida. Stichocapsida.

The cephalis, or the first shell-joint of the Cyrtoidea, is in the majority homologous with the cephalis of the Spyroidea, from which it differs in the reduction of the sagittal ring and the absence of the corresponding sagittal constriction; its cavity is therefore simple, not bilocular. Its homology with the original cephalis of the Spyroidea cannot be doubted, when its base exhibits the typical basal pores of the Semantida. But in many cases these are wanting, and in a great number of Cyrtoidea (mainly of Monocyrtida) there is more or less evidence that the original cephalis is lost, and that the real first joint is the thorax, the original second joint. At present it is quite impossible to distinguish between the former and the latter shells, and therefore in the following descriptions the first joint is always named cephalis and the second thorax. In future, when the affinities of the Cyrtoidea become better known, it will be necessary to distinguish the "Archicephalis," or true cephalis of all Spyroidea and of the majority of Cyrtoidea, from the "Pseudocephalis" or the false cephalis of the minority (e.g., of many Monocyrtida aperta, Archipilida, Archiphormida, Archicorida, &c.).

The thorax, or the second shell-joint of the Cyrtoidea, is in the majority homologous with the thorax of the Phormospyrida and Androspyrida, and therefore developed by apophyses, which arise from the base of the cephalis and become united by transverse branches forming a lattice-plate. Its size is generally in inverse proportion to that of the cephalis. The more the cephalis becomes reduced, the more the thorax is developed. Its form is very variable, usually three-sided pyramidal or prismatic in the triradiate, polyhedral in the multiradiate, and conical or cylindrical in the eradiate Cyrtoidea. Its terminal mouth is either a simple wide opening, or closed by a lattice-plate. In the majority of Cyrtoidea the thorax is separated from the cephalis not only by the external collar constriction, but also by the internal cortinar septum, a horizontal lattice-plate which exhibits the typical basal pores of the Semantida (usually two smaller jugular and two larger cardinal pores). But this septum is often reduced or perfectly lost, and then the external collar constriction alone indicates the separation of the cephalis and the thorax.

The abdomen, or the third shell-joint of the Cyrtoidea, absent in the Monocyrtida and Dicyrtida (as also in all Spyroidea), occurs constantly in all Tricyrtida and Stichocyrtida. It is a simple large chamber in the Tricyrtida, but forms an annulated body, composed of a variable number of successive joints, in the Stichocyrtida. The constrictions between these joints, and also the lumbar constriction, between abdomen and thorax, are usually provided with a lattice-girdle, projecting into the cavity of the shell, like a diaphragm. Usually this horizontal girdle bears only a single circle of pores, rarely two or more. In many Cyrtoidea it is replaced by a solid horizontal ring of silex, and often it is wanting. It originates by the insertion of the following shell-joint, which takes place not on the terminal mouth of the preceding joint, but somewhat above it.

The annular joints of the Stichocyrtida succeeding the third joint, and very variable in number, may be regarded either as a series of new postabdominal chambers, succeeding the true abdomen, or as secondary joints of the annulated abdomen itself. The latter view may be sustained by the fact that these joints are usually of an indifferent shape, and do not possess the characteristic features which we find in the first three joints, the abdomen, the thorax and the cephalis.

The lattice-work of the shell exhibits in the Cyrtoidea an extraordinary variety, similar to that of the Sphæroidea; it serves in the first place for the distinction of species. The three first joints of the shell are often distinguished by the different character of the lattice-work. The cephalis has usually very small and simple pores. The lattice-work of the thorax is often characterised by radial structures. The pores of the abdomen are usually very numerous and regular. The numerous joints in the annulated abdomen of the Stichocyrtida commonly exhibit little variety.

The closure of the mouth, effected by a convex or horizontal terminal lattice-plate, has a different signification in the Monocyrtida and in the jointed Cyrtoidea. In the Monocyrtida clausa this closing plate is the original cortinar plate or the basal plate of the cephalis. In the jointed Cyrtoidea, however, the lattice-plate which closes the terminal mouth of the thorax or of the abdomen (of the last annular joint in the Stichocyrtida), is produced by central union of the convergent edges, which grow centripetally from the margin of the mouth of the last joint towards its centre.

The radial apophyses arising from the shell of the Cyrtoidea may probably be always derived from that tripodal structure which is found in all Plectoidea, in Cortina and Cortiniscus among the Stephoidea, and in the majority of Spyroidea. Therefore the prototype of this radial structure would be Plagoniscus and Cortina, with four radial spines united in a common point, the cortinar centrum; an ascending apical horn and three descending basal feet. The odd posterior or caudal foot is usually similar in shape to the two paired anterior or pectoral feet, but may be distinguished from these latter by its relation to the apical horn. Very frequently an internal vertical free columella arises in the cephalis, or instead of it an ascending rib in the dorsal wall of the cephalis, which connects the base of the apical horn with the origin of the caudal foot. This is probably the remaining part of the sagittal ring. More rarely also a part of the ventral rod of the latter is preserved, or on the anterior pole of the basal rod of the cephalis an ascending procolumella arises which is inserted on the frontal face of the cephalis, and sometimes prolonged into a nasal horn (the rod, C, of Bütschli). These two odd horns, the posterior apical horn and the anterior nasal horn, are usually different and divergent. In some genera a variable number of accessory radial horns is developed on the convex face of the cephalis. In many hornless genera the free apical horn is lost, but not unfrequently the columella is preserved which connects the caudal foot with that point of the cephalis, in which formerly the apical horn was inserted.

The three primary radial beams, corresponding to the three basal feet of Plectaniscus and Cortina, exhibit in the Cyrtoidea the greatest variety in form and size, and chiefly in their relation to the shell, the latter serving mainly for the distinction of genera. Originally these three cortinar beams arise from the basal plate of the cephalis, the odd caudal foot appearing as a prolongation of the basal rod of that plate, and the paired pectoral feet as prolongations of its coracal rods (between the jugular and cardinal pores). The lattice-work of the thorax is developed usually between the three cortinar feet, more rarely inside or outside of them. Therefore the three beams appear commonly as three divergent ribs in the wall of the thorax, and continue over its basal mouth as three free terminal feet. With the increasing length of the shell and the number of its joints the three radial ribs are also prolonged, and their free distal ends may be prominent at very different points, either as three lateral wings or as three terminal feet. These are either solid spines or lattice-plates, sometimes more or less ramified.

The three radial apophyses are prevalent in the majority of the Cyrtoidea, which we call "Pilocyrtida" (or Cyrtoidea triradiata). Their number increases in the Astrocyrtida (or Cyrtoidea multiradiata). The most frequent cases of multiplication are here caused by the development of six or nine radial apophyses; these may be enclosed ribs, or lateral wings, or terminal feet. In the sexradial Cyrtoidea there are three secondary or interradial apophyses interpolated between the three primary or perradial; in the nine-radial Cyrtoidea, however, there are six adradial apophyses interpolated.

A third and last great group is formed by the Corocyrtida or Cyrtoidea eradiata. These exhibit no radial apophyses, neither enclosed ribs, nor free lateral wings, nor terminal feet. But in a great number of them internal traces of an original triradiate structure are visible, mainly in the cortinar septum between cephalis and thorax; this often exhibits three or four, and sometimes six cortinar or collar pores, of the same typical shape as in the triradial Spyroidea. Sometimes even an internal columella with three radial branches is preserved, as in Axocorys. It is therefore very probable that a great part of these Cyrtoidea eradiata (if not all) may be derived from triradiate or multiradiate ancestral forms, by reduction and loss of the radial apophyses. In another part of this group, mainly in the Monocyrtida eradiata (Cyrtocalpida) it is possible, or even probable, that their eradiate shell has originated independently from Nassellida, and that they have no true relation to radial Cyrtoidea.

The Central Capsule of the Cyrtoidea, first observed by J. Müller (1858), and more fully described in my Monograph (1862), was very accurately examined by Richard Hertwig (1879). His observations were confirmed by numerous new forms, which I was able to examine in well-preserved preparations of the Challenger. The central capsule, according to these, exhibits the same typical shape, which is characteristic of all Monopylea (with porochora and podoconus), and may be derived with the latter from the common ancestral forms, Cystidium and Nassella (= the skeletonless Nassellida). In the majority, however, of Cyrtoidea, the capsule develops on its basal face a number of depending lobes, as were also found in some Spyroidea (and probably also Botryodea). In this respect we may distinguish two main forms of the capsule in the Cyrtellaria, viz., the primary simple, not lobate form, and the secondary lobate form. The central capsule is originally always enclosed in the cephalis, and has there a simple, subspherical, ellipsoidal or ovate form. As soon as their growth increases, and the enclosing cephalis becomes too narrow, it sends out prolongations in the form of basal lobes, which depend from its base, and proceed through the pores of the basal lattice of the cephalis, or the cortinar pores. In the great majority of Cyrtoidea in which the capsule was observed, either three or four such lobes were seen (already described by J. Müller). Of course this number depends upon the number of cortinar pores, which is either three or four; therefore in the Cyrtoidea with three pores in the cortinar plate, we find three lobes of the central capsule (an odd posterior and two paired anterior); in the Cyrtoidea, however, with four pores in the cortinar plate (the majority) we find four lobes of the central capsule (two smaller anterior jugular and two larger posterior cardinal lobes). Usually each lobe is ovate or pear-shaped and encloses a large oil-globule, and often also an apophysis of the cell-nucleus.

Section I. MONOCYRTIDA, Haeckel, 1862, Monogr. d. Radiol., pp. 280, 281.

Definition.—Cyrtoidea monothalamia, with simple, not jointed shell (or cephalis), without transverse constrictions.

Synopsis of the three Families and six Subfamilies of Monocyrtida.

Family LIX. Tripocalpida. Three radial apophyses. Mouth open, 1. Archipilida.

Mouth closed, 2. Archiperida.

Family LX. Phænocalpida. Numerous radial apophyses. Mouth open, 3. Archiphormida.

Mouth closed, 4. Archiphænida.

Family LXI. Cyrtocalpida. No radial apophyses. Mouth open, 5. Archicorida.

Mouth closed, 6. Archicapsida.

Family LIX. Tripocalpida. Three radial apophyses.

Mouth open,

1. Archipilida.

Mouth closed,

2. Archiperida.

Family LX. Phænocalpida. Numerous radial apophyses.

Mouth open,

3. Archiphormida.

Mouth closed,

4. Archiphænida.

Family LXI. Cyrtocalpida. No radial apophyses.

Mouth open,

5. Archicorida.

Mouth closed,

6. Archicapsida.

Family LIX. Tripocalpida, n. fam.

Definition.—Monocyrtida triradiata. (Cyrtoidea with a simple, not jointed shell, representing a simple cephalis, with three radial apophyses.)

The family Tripocalpida, composed of the Archipilida and Archiperida of my Prodromus, comprises those Cyrtoidea in which the lattice-shell is quite simple, without transverse constriction, and bears three radial apophyses. The two subfamilies differ in the shape of the basal mouth, which in the Archipilida is a simple wide opening, in the Archiperida closed by a lattice-plate; the former are here divided into eight, the latter into seven different genera.

Only three species of this family were hitherto described, all three belonging to the Archipilida, viz., (1) Tripocalpis galea (fossil in Barbados, figured by Ehrenberg, 1875, as Halicalyptra galea), (2) Tripodiscium campanula (fossil in Sicily, figured by Stöhr, 1880, as Carpocanium); and (3) Tridictyopus elegans, of which Richard Hertwig gave an excellent description in 1879, with an accurate figure of the central capsule. All the other species of the family (seventy) are new.

The shell in the majority of Tripocalpida is ovate or campanulate, sometimes conical or three-sided pyramidal. Three radial apophyses are constantly distinct, either three lateral wings or three terminal feet; these are usually solid spines, rarely lattice-plates. The top of the shell usually bears an apical horn, rarely two or more horns; often the horn is wanting. The lattice-work of the shell is very various in the different species, and often of a remarkable structure (Pl. 51, figs. 6-8; Pl. 98, figs. 4-8). The cavity of the shell is in all Archipilida, and in a part of the Archiperida (Peridium, Archipera, Archibursa) quite simple. In the other part of the Archiperida, however, constituting the peculiar group of Euscenida (genera 504-507), a vertical columella arises in the centre of the basal plate, and is prolonged upwards in the apical horn; this columella is either simple (Euscenium, Archiscenium) or branched (Cladoscenium, Pteroscenium); in the latter case the ascending branches are disposed in triradiate verticils and are inserted on the inner face of the shell (compare Pl. 53, figs. 11-16, and Pl. 98, figs. 1-4).

The phylogenetic origin of the Tripocalpida may be very divergent, and their morphological affinity to the other Nassellaria is a very complicated problem. The Euscenida (genera 504-507) may be derived directly from the Plagonida (Plagoniscus) or Plectanida (Plectaniscus). The Archibursida (genera 508-510) however, manifest a closer affinity to the Tripospyrida, and may be derived from them by reduction of the sagittal ring and constriction. In these two groups of Archiperida the shell may be regarded as a true cephalis. In the Archipilida, however, where the shell has a wide basal opening and the three radial ribs arise originally from the base of the apical horn, the shell itself may correspond to the thorax of the Dicyrtida, and may be derived from these by loss of the cephalis. This is the more probable, as sometimes a small remnant of the reduced cephalis is preserved (Pl. 98, fig. 8). None of these difficult questions can be answered until a much closer morphological knowledge of the Tripocalpida is acquired.

Synopsis of the Genera of Tripocalpida.

I. Subfamily Archipilida. Basal mouth of the shell a simple wide opening. Shell with three lateral ribs or wings, with or without terminal feet. Three terminal feet. Apex with a horn, 496. Tripocalpis.

No apical horn, 497. Tripodonium.

Six to nine or more terminal feet. No apical horn, 498. Tripterocalpis.

No terminal feet. Apex with a horn, 499. Trissopilium.

No apical horn, 500. Archipilium.

Shell without lateral ribs or wings but with three terminal feet. Feet simple or branched, not latticed. Apex with a horn, 501. Tripilidium.

No apical horn, 502. Tripodiscium.

Feet latticed. Apex with a horn, 503. Tridictyopus.

II. Subfamily Archiperida. Basal mouth of the shell closed by a lattice-plate. Shell in its axis with a free (simple or branched) internal columella, prolonged into an apical horn. Shell with three free feet, without lateral lattice-wings. Columella simple, 504. Euscenium.

Columella branched, 505. Cladoscenium.

Shell with three lateral lattice-wings, connecting the three feet with the horn. Columella simple, 506. Archiscenium.

Columella branched, 507. Pteroscenium.

Shell with simple cavity, without free columella. Three free basal feet. One apical horn, 508. Peridium.

Two or more horns, 509. Archipera.

No apical horn, 510. Archibursa.

I. Subfamily Archipilida. Basal mouth of the shell a simple wide opening.

Shell with three lateral ribs or wings, with or without terminal feet.

Three terminal feet.

Apex with a horn,

496. Tripocalpis.

No apical horn,

497. Tripodonium.

Six to nine or more terminal feet.

No apical horn,

498. Tripterocalpis.

No terminal feet.

Apex with a horn,

499. Trissopilium.

No apical horn,

500. Archipilium.

Shell without lateral ribs or wings but with three terminal feet.

Feet simple or branched, not latticed.

Apex with a horn,

501. Tripilidium.

No apical horn,

502. Tripodiscium.

Feet latticed.

Apex with a horn,

503. Tridictyopus.

II. Subfamily Archiperida. Basal mouth of the shell closed by a lattice-plate.

Shell in its axis with a free (simple or branched) internal columella, prolonged into an apical horn.

Shell with three free feet, without lateral lattice-wings.

Columella simple,

504. Euscenium.

Columella branched,

505. Cladoscenium.

Shell with three lateral lattice-wings, connecting the three feet with the horn.

Columella simple,

506. Archiscenium.

Columella branched,

507. Pteroscenium.

Shell with simple cavity, without free columella. Three free basal feet.

One apical horn,

508. Peridium.

Two or more horns,

509. Archipera.

No apical horn,

510. Archibursa.

Subfamily 1. Archipilida, Haeckel, 1881, Prodromus, p. 427.

Definition.—Tripocalpida with the basal mouth of the shell open (vel Monocyrtida triradiata aperta).

Genus 496. Tripocalpis,^[113] Haeckel, 1881, Prodromus, p. 428.

Definition.—Archipilida (vel Monocyrtida triradiata aperta) with three lateral ribs prolonged into three terminal feet. Apex with a horn.

The genus Tripocalpis opens the series of Archipilida, or of those Monocyrtida in which the monothalamous shell exhibits a distinct triradial structure, and a simple open mouth, without cortinar lattice. Tripocalpis is probably the most primordial of the Archipilida, and has three lateral ribs, which are prolonged into three free terminal feet, and connected in the apex of the pyramidal or campanulate shell with the apical horn. It may probably be derived from Dictyophimus by loss of the cephalis. The central capsule is simple, spherical, or ellipsoidal.

1. Tripocalpis plectaniscus, n. sp.

Shell three-sided pyramidal, smooth, about as long as broad, with irregular polygonal pores and thin bars. Apical horn stout, three-sided pyramidal, about as long as the shell. From the three edges of its base arise three prominent straight radial ribs, which are prolonged into three large divergent feet, of equal size and the same form as the horn.

Dimensions.—Shell 0.1 diameter, horn and feet 0.12.

Habitat.—Tropical Pacific (Philippine Sea), Station 206, depth 2100 fathoms.

2. Tripocalpis galea, Haeckel.

Halicalyptra galea, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 74, Taf. ii. fig. 10.

Shell campanulate, rough, about as long as broad, with irregular roundish pores and thick bars. Apical horn stout, three-sided pyramidal, scarcely one-fourth as long as the shell. Beyond its base there arise three prominent, slightly curved lateral ribs, which are prolonged into three pyramidal, slightly divergent stout feet, somewhat shorter than the shell.

Dimensions.—Shell 0.08 to 0.09 diameter, horn 0.02, feet 0.07.

Habitat.—Fossil in Barbados.

3. Tripocalpis tricostata, n. sp.

Shell ovate campanulate, one and a half times as long as broad, with regular circular pores, disposed in alternate longitudinal rows. Apical horn three-sided pyramidal, stout, half as long as the shell. In the middle of the shell there arise three wing-like lateral ribs, which are prolonged into three broad, slightly curved, divergent terminal feet.

Dimensions.—Shell 0.12 long, 0.08 broad, horn and feet 0.06 to 0.08.

Habitat.—Fossil in Barbados.

4. Tripocalpis triserrata, n. sp. (Pl. 51, fig. 6).

Shell ovate, nearly twice as long as broad. The three sides of the shell, between the three large ribs, are provided each with nine delicate parallel, longitudinal, slightly curved ribs, alternating with ten longitudinal rows of regular circular pores about as broad as the bars. Apical horn short and broad, three-sided pyramidal; from the three edges of its base there arise three wing-like serrate main ribs, which are prolonged into three short pyramidal terminal feet.

Dimensions.—Shell 0.12 long, 0.07 broad, horn and feet 0.01.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

5. Tripocalpis cortinaris, n. sp. (Pl. 97, fig. 3).

Shell hemispherical, one and a half times as broad as long, with regular, circular, hexagonally framed pores, Apical horn stout, three-sided pyramidal, with three serrate edges. From the base of the latter arise three strongly dentate and curved lateral ribs, with recurved teeth, and these are prolonged into the serrate convex edge of the three basal feet, which are crescentic and twice as long as the shell.

Dimensions.—Shell 0.07 long, 0.1 broad; horn 0.06 long, feet 0.14 long.

Habitat.—Indian Ocean, Cocos Islands (Rabbe), surface.

Genus 497. Tripodonium,^[114] Haeckel, 1881, Prodromus, p. 428.

Definition.—Archipilida (vel Monocyrtida triradiata aperta) with three lateral ribs prolonged into three terminal feet. Apex without horn.

The genus Tripodonium differs from the preceding Tripocalpis, its probable ancestral form, only in the loss of the apical horn (already very small in some forms of the latter). It bears therefore to the latter the same relation that Sethopilium does to Dictyophimus.

1. Tripodonium campanulatum, n. sp.

Shell campanulate, somewhat broader than high, with regular circular pores, twice as broad as the bars. Three broad lateral wings, lamellar, triangular, are prolonged over the peristome into three short triangular lamellar feet one-fourth as long as the shell.

Dimensions.—Shell 0.08 long, 0.09 broad; feet 0.02 long.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

2. Tripodonium ovatum, n. sp.

Shell ovate, one and one-third times as long as broad, with numerous and small circular pores, scarcely as broad as the bars. Three prominent longitudinal ribs, arising in the lower half of the shell-wall, are prolonged into three divergent conical curved feet, about half as long as the shell.

Dimensions.—Shell 0.12 long, 0.09 broad; feet 0.06 long.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

Genus 498. Tripterocalpis,^[115] Haeckel, 1881, Prodromus, p. 428.

Definition.—Archipilida (vel Monocyrtida triradiata aperta) with three lateral wings and a peristomial corona of numerous terminal feet. Shell ovate, with constricted mouth, without apical horn.

The genus Tripterocalpis is distinguished from the other Archipilida by the remarkable combination of three lateral wings and of numerous (six to nine or more) terminal feet. It may be derived directly from the preceding Tripocalpis by multiplication of the terminal feet. These are sometimes obliquely directed. The central capsule is ellipsoidal or ovate, and fills up the greater part of the shell.

1. Tripterocalpis phylloptera, n. sp. (Pl. 51, fig. 1).

Shell slender, ovate, nearly twice as long as broad. Pores circular, of different sizes and at unequal distances. Along the lower half of the shell there arise three broad triangular lamellar wings. Peristome with twelve conical, nearly parallel and vertical feet, about one-sixth as long as the shell.

Dimensions.—Shell 0.2 long, 0.12 broad; wings 0.1 long, feet 0.03 long.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

2. Tripterocalpis conoptera, n. sp. (Pl. 51, fig. 2).

Shell ovate, nearly as broad as long. Pores regular, circular, quincuncial, twice as broad as the bars. In the middle of the shell there arise three conical, smooth, divergent wings, about half as long as the shell. Peristome with six short triangular, oblique, convergent feet.

Dimensions.—Shell 0.16 long, 0.14 broad; wings 0.09 long; feet 0.02 long.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

3. Tripterocalpis ogmoptera, n. sp. (Pl. 51, figs. 3-5).

Shell ovate, nearly as broad as long. Pores small and numerous, circular or roundish, partly confluent, double-contoured (fig. 4). In the middle of the shell there arise three very large conical divergent wings, which are longitudinally striped and longer than half the shell. Peristome with nine short triangular, oblique, convergent feet.

Dimensions.—Shell 0.18 long, 0.16 broad; wings 0.12 long, feet 0.02 long.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Genus 499. Trissopilium,^[116] Haeckel, 1881, Prodromus, p. 427.

Definition.—Archipilida (vel Monocyrtida triradiata aperta) with three lateral ribs or wings. Mouth smooth, without terminal feet. Apex with a horn.