DESCRIPTION OF PLATES.
Reading edition
PLATE 1. BALANUS TINTINNABULUM.
Fig. a, b, and f (upper shell), Balanus tintinnabulum,—var. communis.
c and f (part of shell), ”””validus.
d,””””coccopoma.
e,””””concinnus.
f (part of shell),”””validus.
g,””””zebra.
h,””””crispatus.
i,””””spinosus.
k,””””occator.
l,””””d’Orbignii.
PLATE 2. Genus—BALANUS.
Fig. 1 a,Balanus tintinnabulum,—var. communis, scutum.
1 b,”””occator”
1 c, 1 d, and 1 e,”””communis”
1 f,”””coccopoma”
1 g,”””concinnus”
1 h, (magnified)””(young)” vesiculosus”
1 i, and 1 k,”””communis, tergum.
1 l,”””coccopoma”
1 m, and 1 n,”””d’Orbignii”
1 o,”””coccopoma”
2 a, 2 b, 2 c, 2 d, Balanus tulipiformis, scutum and tergum, external and internal views of.
3 a, 3 b, 3 c, 3 d, Balanus psittacus, scutum and tergum, external and internal views of.
4 a, 4 b, Balanus Capensis, scutum and tergum, internal view of.
5 a, 5 b, Balanus nigrescens””
6 a, Balanus decorus, scutum, internal view; 6 b, tergum, external view.
7 a, Balanus vinaceus, scutum, internal view; 7 b, do. external view; 7 c, tergum, external view; 7 d, basal edge of the parietes of one of the compartments, showing the cancellated structure of the inner lamina.
PLATE 3. Genus—BALANUS.
Fig. 1 a, Balanus Ajax; 1 b, scutum external; 1 c, tergum external; and 1 d, scutum, internal view.
2 a, 2 b, Balanus stultus, scutum and tergum, external views; 2 c and 2 d, scutum, internal and external views.
3 a, Balanus calceolus; 3 b, variety; 3 c, scutum, internal view; 3 d, tergum, internal view; 3 e, spur of tergum toothed.
4 a, Balanus galeatus; 4 b, 4 c, scutum and tergum, internal view.
5 a, 5 b, Balanus cymbiformis, scutum and tergum, internal view.
6 a, Balanus navicula; 6 b, 6 c, scutum and tergum, internal view; 6 d, scutum, external view.
7 a, Balanus trigonus; 7 b and 7 c, scutum, external views, two varieties; 7 d, scutum, internal view; 7 e and 7 f, tergum, external views, two varieties.
PLATE 4. Genus—BALANUS.
Fig. 1 a and 1 b, Balanus spongicola, external views of scutum and tergum; 1 c, var. of the tergum, from a specimen from the Cape of Good Hope; 1 d, var. of the tergum from the West Indies.
2, Balanus lævis.
2 a,””fossil, elongated var., showing lower part of basal cup filled up with a cancellated mass.
2 b and 2 c,””scutum, external and internal view of.
2 d and 2 e,””scutum (variety), internal and external view of.
2 f,””scutum (variety), external view.
2 g,””tergum, external view.
3 a, Balanus perforatus, scutum, internal view; 3 b, tergum, internal view; 3 c, tergum, var. external view.
4 a, Balanus concavus (var. from Panama), scutum, internal view; 4 b, scutum, external view; 4 c, tergum, external view; 4 d, tergum, fossil, Coralline Crag; 4 e, tergum, fossil, Italy.
PLATE 5. Genus—BALANUS.
Fig. 1 a, Balanus perforatus,—var. angustus.
1 b,”””Cranchii.
1 c,”””mirabilis.
1 d,”””fistulosus.
2 a,”amphitrite,—var. venustus.
2 b,””var. cirratus.
2 c,””” pallidus.
2 d,””” Stutchburii.
2 e,””” communis.
2 f,””” niveus.
2 g,””” obscurus.
2 h,”” scutum, var. communis.
2 i,”””” Stutchburii.
2 k,”” tergum,” pallidus.
2 l,”””” communis.
2 m, 2 n, and 2 o,””var. Stutchburii.
3 a, Balanus pœcilus, scutum, internal view; 3 b, tergum, external.
4 a, Balanus eburneus, scutum, external view; 4 b, tergum, external; 4 c, scutum, internal; 4 d, tergum (var.), internal.
PLATE 6. Genus—BALANUS.
Fig. 1 a, Balanus improvisus; 1 b, scutum, internal; 1 c, tergum, external view.
2 a, Balanus nubilus, scutum, internal view; 2 b, tergum, ditto; 2 c, tergum, external view.
3 a, 3 b, Balanus corrugatus, scutum and tergum, internal view.
4 a, Balanus porcatus; 4 b and 4 c, scutum and tergum, internal views; 4 d, tergum external; 4 e, basal edge of the parietes of wall of shell.
5 a, Balanus patellaris; 5 b, scutum, internal; 5 c, tergum, external.
6 a, Balanus crenatus.
6 b,””smooth var.
6 c,””elongated var.
6 d and 6 e,”scutum and tergum, external views.
6 f and 6 g,”””internal views.
PLATE 7. Genus—BALANUS.
Fig. 1 a, Balanus glandula, scutum, internal; 1 b, tergum, external.
2 a, Balanus balanoides; 2 b, portion of basal edge of parietes of a compartment; 2 c, tergum; 2 d, tergum, var.
3 a, Balanus cariosus; 3 b, portion of basal edge of parietes of a compartment; 3 c, scutum, internal view of; 3 d, tergum, internal; 3 e, tergum, external view.
4 a, Balanus declivis, lateral view, with basal membrane removed; 4 b, rostrum (to left hand), two lateral compartments, and carina; 4 c and 4 d, scutum and tergum, external views.
5 a, Balanus Hameri; 5 b, scutum, internal view; 5 c, tergum, external view.
6 a, Balanus amaryllis; 6 b, scutum, internal; 6 c, tergum, external view.
7 a, Balanus allium; 7 b and 7 c, scutum, external and internal views; 7 d, tergum, external.
8 a, Balanus cepa, scutum, internal; 8 b, scutum, external; 8 c, tergum, external view.
PLATE 8. Genus—BALANUS.
Fig. 1, Balanus quadrivittatus.
2 a, Balanus terebratus, part of basis seen from the outside; 2 b, the same, seen from within.
3 a, Balanus vestitus, scutum, internal view; 3 b, tergum, external view.
4 a, Balanus imperator, scutum, internal view; 4 b, tergum, external view; 4 c, portion of basal edge of wall of the shell.
5 a, Balanus flosculus.
5 b,””var. sordidus.
5 c,””scutum, internal view.
5 d,””””var.
5 e and 5 f,”tergum, internal and external views of.
6 a, Balanus bisulcatus, scutum, external view; 6 b, tergum, external view; 6 c, scutum, internal view.
7, Balanus dolosus, tergum, external view.
8 a, Balanus unguiformis, scutum, internal view; 8 b, tergum, do.
9, Balanus varians, tergum, external view.
10 a, Balanus inclusus.
10 b,””var. that has been attached to a branch of a coralline.
10 c,”””seen from beneath, showing the narrow furrowed basis and wide lateral compartments; the other four compartments, namely, the two carino-lateral, the carina, and rostrum, being of very small size.
PLATE 9. Sub-Genus—ACASTA.
Fig. 1 a, Acasta spongites; 1 b, scutum, external view; 1 c, scutum, internal; 1 d, tergum, internal.
2 a, Acasta sulcata; 2 b, var., lateral compartment of; 2 c and 2 d, terga, internal views of two varieties.
3 a, Acasta cyathus; 3 b and 3 c, scutum and tergum, internal views.
4, Acasta undulata, scutum, external view.
5 a, Acasta glans, basis seen from within; 5 b, compartments of a smaller specimen, seen from within; carina on the right-hand, cut into two; carino-lateral and lateral compartments to the left-hand; 5 c, tergum, internal view.
6 a, Acasta lævigata, tergum, internal view; 6 b, another var.
7 a, Acasta fenestrata; 7 b, scutum, and 7 c, tergum, internal views.
8 a, Acasta purpurata; 8 b, scutum; 8 c, tergum, internal views.
9 a, Acasta sporillus; 9 b, carino-lateral compartment (almost rudimentary) and lateral compartment, seen from within; 9 c and 9 d, scutum and tergum, seen from within.
PLATE 10. Genus—TETRACLITA.
Fig. 1 a, Tetraclita porosa, var. communis.
1 b,”””rubescens.
1 c,”””nigrescens.
1 d,”””elegans.
1 e,”””communis, young, with radii developed.
1 f,”””patellaris.
1 g,””basal edge of wall of shell.
1 h,””basal edge of wall of shell, var. elegans, showing also the structure of one of the rudimentary radii or sutures.
1 i,””internal view of scutum; 1 k, do. of tergum; 1 l, do. of scutum, var.; 1 m, do. of tergum, var.
2 a, Tetraclita serrata; 2 b, portion of external surface of wall, low down, near basis; 2 c and 2 d, scutum and tergum, internal views.
3 a, Tetraclita rosea, scutum; 3 b, tergum; 3 c, whole shell; 3 d, basal edge of wall of shell.
PLATE 11. Genera—TETRACLITA AND ELMINIUS.
Fig. 1 a, Tetraclita purpurascens, var. with surface disintegrated, and with the sutures united and obliterated.
1 b, Tetraclita purpurascens, var. well preserved, with the radii developed; 1 c and 1 d, var. scutum and tergum, internal views.
2 a, Tetraclita costata; 2 b and 2 c, scutum and tergum.
3 a, Tetraclita vitiata; 3 b, basal edge of portion of wall; 3 c and 3 d, scutum and tergum, internal views of; 3 e, tergum, internal view, var.
4 a, Tetraclita cœrulescens; 4 b, scutum and tergum united, external view; 4 c and 4 d, scutum and tergum, internal views.
5 a, Tetraclita radiata; 5 b, scutum and tergum united, external view; 5 c and 5 d, scutum and tergum, internal views.
6 a, Elminius Kingii; 6 b and 6 c, scutum and tergum, internal views of; 6 d, tergum, var. external view of; 6 e, tergum, another var. internal view of.
PLATE 12. Genera—ELMINIUS AND PYRGOMA.
Fig. 1 a, Elminius modestus; 1 b, scutum, internal view; 1 c, tergum, internal view; 1 d, do., tergum, var.; 1 e, do., tergum, var.
2 a, Elminius plicatus; 2 b, basal edge of portion of wall of shell; 2 c and 2 d, scutum and tergum, internal views of; 2 e and 2 f, scutum and tergum, internal views of, var.
3, Elminius simplex; shell.
4 a, Pyrgoma Anglicum; 4 b and 4 c, scutum and tergum, internal views.
5 a, Pyrgoma cancellatum, shell, seen from above; 5 b, shell seen on the under side; 5 c and 5 d, scutum and tergum, external views; 5 e and 5 f, scutum and tergum, internal views of.
6, Pyrgoma Stokesii, shell imbedded in coral.
7 a, Pyrgoma conjugatum, shell, external view of; 7 b, scutum and tergum, calcified together, seen from the outside; 7 c, do., internal view of.
PLATE 13. Genera—PYRGOMA AND CREUSIA.
Fig. 1 a, Pyrgoma grande; 1 b, scutum and tergum, calcified together, external view of; 1 c, scutum and tergum, internal view of; 1 d, the two scuta and terga, external view, seen from above, having their natural position, when closed.
2 a, Pyrgoma milleporæ, shell viewed from above; 2 b, internal view of, showing the sheath; 2 c, scutum and tergum, united, external view of; 2 d, scutum, var. external view of; 2 e, scutum, internal view of; 2 f, tergum, internal view of.
3 a, Pyrgoma dentatum shell, external view of; 3 b, scutum, var. 1, external view of; 3 c, tergum, var. 1, external view of; 3 d, tergum, var. 2, external view of; 3 e, scutum, var. 3, external view of; 3 f, tergum, var. 3, external view of; 3 g, scutum and tergum, var. 1, joined together, internal view of.
4 a, Pyrgoma crenatum, scutum, external view of, showing the great depending adductor plate and large occludent ledge; 4 b, external view of.
5 a, Pyrgoma monticulariæ, external view of; 5 b, another specimen, internal view of; 5 c, another specimen, external view of; 5 d, portion of circumference of shell, viewed externally, much magnified, showing the outer lamina, and the irregular, longitudinal septa; 5 e, another specimen of the same, with the longitudinal septa more regular; 5 f, scutum and tergum completely calcified together, external view of.
6 a, Creusia spinulosa, shell, seen from above.
6 b, 6 c, Creusia spinulosa, var. 1, scutum and tergum, internal view of; 6 d, scutum and tergum, joined together, external view of.
6 e, 6 f, 6 g, Creusia spinulosa, var. 2, 6 e, scutum, internal view; 6 f, tergum, internal view of; 6 g, tergum, of another specimen, internal view of.
6 h, Creusia spinulosa, var. 3, scutum and tergum joined together, external view of.
PLATE 14. Genera—CREUSIA AND CHELONOBIA.
Fig. 6 i, 6 k, 6 l, Creusia spinulosa, var. 4, 6 i, tergum, external view; 6 k, the same, from another individual; 6 l, the same, internal view.
6 m, Creusia spinulosa, var. 5, tergum, external view.
6 n, 6 o, 6 p, 6 q, Creusia spinulosa, var. 6, 6 n, scutum, external view of; 6 o, tergum of same individual, external view of; 6 p, scutum of another individual, external view of; 6 q, tergum of latter, external view of.
6 r, Creusia spinulosa, var. 7, scutum, internal view of.
6 s, Creusia spinulosa, var. 9, scutum and tergum, calcified together, external view.
6 t, Creusia spinulosa, var. 10, scutum and tergum, calcified together, external view.
6 U, Creusia spinulosa, var. 11, shell seen from above; 6 u, scutum and tergum, calcified together, external view.
Fig. 1 a, Chelonobia testudinaria, shell seen from above; a specimen has been chosen, with some of the radii smooth, and others more or less notched; 1 b, scutum, internal view of; 1 c, tergum, internal view of; 1 d, scutum and tergum, joined together, external view of.
2, Chelonobia caretta, shell seen from above.
3 a, Chelonobia patula, shell seen from above; 3 b, tergum, external view of.
4, Carina of Chelonobia patula, seen from within; a a, outer lamina of wall, joined by the longitudinal septa to b, the inner lamina; e c e, sheath, descending to the base of shell, with the middle part largely hollowed out; the upper part of the sheath, above d d, is transversely marked by the lines of attachment of the opercular membrane; d, d, alæ.
5, View of the edge of the radius of the rostrum of Chelonobia testudinaria.
a, a, inner portion of radius.
b, thick outer lamina of the radius, transversely pitted; beneath this pitted portion, which forms only the outer surface of the radius, and distinct from the inner portion a, the arborescent and dentated sutural edges of this outer lamina are seen.
c, outer lamina of wall of compartment.
d, the exterior septum, connecting the outer lamina of the wall to the inner lamina; the basal edge of the inner lamina of the wall is seen beneath and without the lower end of the inner portion (a) of the radius.
PLATE 15. Genera—CHELONOBIA AND CORONULA.
Fig. 1, Transverse section of shell of Chelonobia testudinaria.
B A B, Compound rostrum: A being the true rostrum.
B B, the rostro-lateral compartments, which normally, in the Balaninæ, are quite confounded with the true rostrum: the sutures separating these three compartments are not continued through the outer lamina.
C, left-hand lateral compartment.
D, left-hand carino-lateral compartment.
E, carina.
S S, Sutures, six in number, separating the six compartments.
a, outer lamina of wall of compartment, whence the radiating, longitudinal septa (left unshaded) arise, and at the opposite end blend into the indistinct inner lamina, viz. b, (see fig. 4, in last plate.)
c′, sheath.
d, ala, forming, as usual, part of the sheath.
e, inner portion of the radius.
f, f, outer lamina of the radius (see b, in fig. 5, in last plate), of great thickness, and externally deeply pitted;—the sharp ridges between the pits, produce in the section the points, such as that marked by the outer f.
2, Coronula balænaris, shell seen from above.
2 a,””section of one of the transverse circumferential loops, formed by the folded wall of a compartment. The wall itself is formed of an outer and inner lamina, with longitudinal septa. The internal surfaces of the loop-part are connected by special shelly plates or longitudinal septa.
2 b,””scutum and tergum united together by the opercular membrane (with horny ridges), seen from the inner side.
3, Coronula diadema, shell, seen from the outside; 3 a, scutum and tergum joined together by the opercular membrane, seen from the outside; 3 b, scutum cleaned and enlarged, seen from the inside.
4, Section, in a vertical plane, through the skin of a whale, on which a Coronula diadema had been attached, but has been wholly removed: the two curved, horn-like projections occupied two of the eighteen cavities on the under side of the shell, formed by the folded walls: the blacker part is the epidermis; the lighter part is the yellowish fibrous tissue of the skin under the epidermis.
5, Coronula reginæ, shell seen from the outside.
6, Coronula barbara, internal view of the basal margin and inside of one of the compartments, exhibiting the circumferential transversely looped ends of the folds of the wall, with the inner surface transversely wrinkled.
7-9, diagrams, showing how one of the circumferential transverse loops of the wall becomes divided into two transverse loops, thus giving rise to another fold in the wall.
10, diagrams, showing how the wall of the young shell in Coronula, from being (a) simply sinuous, becomes deeply folded (b); the folds lastly (c) expanding transversely at their ends, thus giving rise to the circumferential transverse loops, as in fig. 7.
PLATE 16. Genus—CORONULA.
Fig. 1, rostrum, viewed from the inner side, of Coronula diadema.
a, sheath, marked transversely in the upper part by the attachment of the opercular membrane.
b, furrow on each side of (a), receiving the edges of the thick alæ of the adjoining lateral compartments.
c′′, special plate, on which the alæ on their outer sides rest.
d, radius, on the edge it may be just seen to consist of an outer layer (the normal radius), and a much thicker inner part (the pseudo or complementary radius) formed of oblique denticulated septa.
e e′ e′′, basal edge of wall, which from its commencement at e, or e′′ can be followed, folding up to near the basal edge of the sheath, to its termination at e′′ or e.
f, serrated lines of junction between the folds of the wall.
2, Lateral compartment of C. diadema, seen laterally, on a smaller scale than last fig., but taken from the same shell; letters of reference the same: this figure, if the ala a′ were removed, would do for a lateral view of the rostrum, or fig. 1.
a, sheath, much foreshortened.
a′, ala (therefore also part of sheath), and the edge of which fits into b of fig. 1.
b, furrow receiving edge of ala of the adjoining carino-lateral compartment.
c′′, special plate, seen edgeways.
d, radius, the division into two parts, viz., the thin outer normal radius, and the under pseudo or complementary radius here shown (rather exaggerated) plainer than in fig. 1.
e, basal edge of wall; to the right hand the three folds at their inner ends are seen obliquely, one behind the other: these are seen directly in front in fig. 1.
3, lateral compartment of C. balænaris, seen laterally; letters of reference the same as in last fig., but c′′ not introduced for this plate is barely developed, and only in the lower part, and is attached to the radius: g g points where fresh folds have been formed in the walls along the lines of suture, as may be seen in the outline of the wall in fig. 5.
4, lateral compartment of C. reginæ, seen laterally; letters of reference the same as in the last two figures.
5, Coronula balænaris, outline of the basal margin of the folded walls: s, s, the six sutures. The wall can be continuously followed from one end of a suture to the next suture.
6, Coronula diadema; small portion of the external surface of the wall, close to the basal edge, highly magnified; a, outer lamina, not extending down to the basal edge; b, inner lamina; c, projecting longitudinal septa.
7, Coronula diadema; transverse section through the upper part of the shell, showing the rostrum and the two adjoining lateral compartments (and the alæ of the carino-lateral compartments), all supposed to be a little separated from each other, so that the sutures, s s, are shown by white lines.
A A A, rostrum.
C C, lateral compartments.
D D, carino-lateral compartments, of which only the alæ (a′) are shown.
Of the letters in italics, those which occur in figs. 1, 2, 3, 4, 5, refer all to the same parts, viz.:—
a, sheath, continuous with (a′) the alæ, where such occur.
c′′, special plate on which the alæ rest.
d, radius, divided into a thin outer normal radius, and the inner complementary portion, the latter shaded by convex lines of growth.
d′ is a special tube (seen only as a black dot) for a thread of corium.
e, folded walls.
f, junction of the folded walls (see f, in fig. 1) leading into the cavities (f′) open beneath, and filled up by the epidermis (see Pl. 15, fig. 4) of the whale.
h, inside of the transverse loops of wall, occupied by corium: in the enlarged section of a loop, in C. balænaris, in Pl. 15, fig. 2 a, the opposed sides are seen to be connected by shelly longitudinal plates.
v, cavity occupied by the ovarian tubes and cæca.
PLATE 17. Genera—PLATYLEPAS, TUBICINELLA, AND XENOBALANUS.
Fig. 1 a, Platylepas bissexlobata, shell of, viewed from the under side; A, rostrum; B, lateral compartment; C, carino-lateral compartment; E, carina. These letters are placed opposite the inward folds of each compartment forming the midribs.
1 b, Platylepas bissexlobata, shell of, viewed externally.
1 c,””scutum and tergum, viewed externally and separated.
1 d,””lateral compartment, viewed from the inside, showing the inward folded wall or midrib; a′, ala; d, radius.
2 a, Platylepas decorata, shell, viewed externally; A, rostrum; B, lateral compartment; C, carino-lateral compartment; E, carina. These letters are placed opposite the inward folds of each compartment.
2 b,””minute portion of external surface of wall, magnified.
3 a, Tubicinella trachealis, natural size; p, tubular soft lip leading into sack; s, scutum; t, tergum.
3 b, Tubicinella trachealis, carino-lateral compartment of a young specimen, natural size; e, broken summit of wall; d, radius: the dotted lines, connecting the two figures, show the size and form which this compartment would have attained, if it could have grown without the summit constantly breaking away.
3 c, Tubicinella trachealis, scutum and tergum viewed from within, and connected by layers of thickened membrane; the scutum is to the left-hand.
4 a, Xenobalanus globicipitis, enlarged; b, skin of the porpoise, with the shell imbedded; at c the lower end of the prosoma of the included animal’s body is supposed to be seen through.
4 b, Xenobalanus globicipitis, shell greatly enlarged, seen from above, with the basal membrane at the bottom; the peduncle-formed body having been removed.
A, rostrum, on the inner side of this and the adjoining compartments, the transversely ribbed sheath can be seen.
B, lateral compartment.
C, carino-lateral compartment.
E, carina; these compartments are separated by the sutures s s, which run from the top of the shell to the bottom, along the ends of the six rays formed by the adjoining portions of the inwardly folded compartments.
a, alæ, of rectangular shape.
d, pseudo, or complimentary radii.
4 c, Xenobalanus globicipitis, small portion of external surface of wall of shell, showing the external lamina, a a, which consists only of narrow ledges (expanding and contracting) on each side of the longitudinal septa, c; b, the internal lamina.
PLATE 18. Genus—CHTHAMALUS.
Fig. 1 a, Chthamalus stellatus, shell, var. a (communis).
1 b,”””” e (depressus).
1 c,”””” c (communis).
1 d,”””” d (fragilis).
1 e,””scutum and tergum, viewed inside, var. c, British.
1 f,””scutum and tergum, viewed inside, var. a, Madeira.
1 g,””scutum and tergum, viewed inside, var. e, Mediterranean.
1 h,””scutum and tergum, viewed inside, var. c and e, St. Jago, Cape de Verde Arch.
2, Chthamalus antennatus, shell.
3 a, Chthamalus dentatus, shell; 3 b, var. shell, attached to a ship’s bottom; 3 c, tergum, viewed from within.
4 a, Chthamalus cirratus, scutum, viewed on inside; 4 b, tergum, viewed on inside.
5 a, Chthamalus Hembeli, shell, old specimen.
5 b, Chthamalus Hembeli, younger shell; C, carino-lateral compartment; a′, ala; d, radius; E, carina; a′, the two alæ.
5 c, Chthamalus Hembeli, scutum, external view of; 5 d, tergum, external view of; e, two of the crests, to which the tergal depressor muscles are attached, much enlarged and viewed from vertically beneath, showing the lateral denticuli or sub-crests.
6 a, Chthamalus fissus, shell; 6 b, scutum and tergum, separated, internal views of.
PLATE 19. Genera—CHTHAMALUS, CHAMÆSIPHO, AND PACHYLASMA.
Fig. 1 a, Chthamalus intertextus, shell; 1 b, scutum and tergum, calcified together, with the suture obliterated in the upper part, internal view of.
2 a, Chthamalus scabrosus, shell; 2 b, scutum, internal view of; 2 c, tergum, internal view, p, plate forming one side of the cavity in which the depressor muscle is attached; 2 d, tergum, as seen from almost vertically beneath; p, pit for the depressor muscle; q, special pit for the lateral, properly scutal depressor muscle; r, articular furrow.
3 a, Chamæsipho columna, shell; A, rostrum; B, lateral compartment, probably formed by fusion of the rostro-lateral and lateral compartments; E, carina; 3 b, 3 c scutum and tergum, internal views of.
4 a, Chamæsipho scutelliformis, shell much enlarged, seen from above; A, rostrum, separated by imperfect sutures from the (B) lateral compartments, which are formed probably by the fusion of the rostro-lateral and lateral compartments; E, carina; B stands opposite one of the inward folds of the wall, leading into one of the tubular apertures, which runs (generally with an irregular spiral curve) through the whole thickness of the shell down to the surface of attachment. The carina has two of these apertures.
4 b, Chamæsipho scutelliformis, another specimen, seen from the under side, letters of reference the same.
4 c, Chamæsipho scutelliformis, rostrum, disarticulated, enlarged, showing the alæ.
4 d, Chamæsipho scutelliformis, scutum and tergum, internal views of.
5 a, Pachylasma giganteum; 5 b, rostrum of an extremely young specimen, much enlarged, showing its compounded nature, viz., of a true rostrum and rostro-lateral compartments; 5 c, scutum and tergum, external views of; 5 d, scutum and tergum, internal views of.
PLATE 20. Genera—PACHYLASMA, OCTOMERIS, AND CATOPHRAGMUS.
Fig. 1 a, Pachylasma aurantiacum, shell, lateral view; A, rostrum, separated only by the finest suture from B, the rostro-lateral compartment, which latter has a mere rim-like radius on the side facing the lateral (C) compartment. The latter (C) has a great ala, and is separated from the (D) carino-lateral compartment, by the finest suture; D has a rim-like radius; E, carina, with very large alæ (a).
1 b, Pachylasma aurantiacum, inside view of about half the shell, showing the compound rostrum, consisting of the true rostrum (A) and the two rostro-lateral (B, B) compartments; of the latter, that to the left has a shoulder, receiving the ala of the lateral compartment which has been removed; the ala of the lateral compartment extends, in the upper part, over the whole width of the rostro-lateral compartment, as may be seen on the right-hand, B; C, lateral compartment; D, carino-lateral compartment, with a shoulder (b) to receive the ala of the carina, which has been removed.
1 c, 1 d, Pachylasma aurantiacum, scutum and tergum, external views of.
2 a, Octomeris angulosa, shell seen from above; 2 b, scutum and tergum, internal views of.
3 a, Octomeris brunnea, shell seen from above; 3 b, scutum and tergum, external views of.
4 a, Catophragmus polymerus, shell seen from above.
4 b,””external view of one of the scales or valves, from the second whorl, counting from the inside.
4 c,””outline of the basal edges of all the valves of a shell; A, rostrum; B, rostro-lateral; C, lateral; D, carino-lateral compartments; E, carina.
4 d,””external view of a portion of the shell of a much corroded and worn down specimen, serving almost as a transverse section; C, lateral compartment, D, carino-lateral compartment.
4 e,””scutum and tergum, internal views of.
PLATE 21. Genus—VERRUCA.
N.B.—Letters of reference the same throughout the Plate.
A, rostrum.
B, carina.
S, moveable scutum, S′, scutum fixed and modified so as to form part of the shell.
T, moveable tergum, T′, tergum fixed and modified so as to form part of the shell.
In S, and S′, a is the occludent margin; b, the basal margin; m, the plate to which the adductor muscle is fixed; o, a ledge formed during continued growth, in the upper part of the fixed scutum, in order to keep the orifice perfectly closed; this ledge is seen distinctly only in fig. 5.
In S and S′ the tergal margin is marked by small dashes; (′) being the upper articular ridge, and (′′), the second or lower articular ridge: in S′ (′′) is called the parietal portion of the valve.
In T and T′, the scutal margin is marked by small dashes; (′) being the first and upper articular ridge, hardly distinct from the occludent margin, and called in T′′ the occludent rim; (′′) is the second or middle, and (′′′) the lower or third articular ridge, called in T′′ the parietal portion of the valve; x is the carinal margin, called in T′ the carinal rim, and z the basal margin; o is the occludent margin: in T′, a ledge is formed across the under side close to the apex, which ledge is necessary to keep the orifice neatly closed, owing to the apex of the moveable tergum coming to project freely during growth.
Fig. 1 a, Verruca Strömia, specimen with the left hand scutum and tergum fixed and modified into part of the shell.
1 b, Verruca Strömia, (with left hand scutum and tergum fixed), with the valves and compartments separated from each other; the homologous parts of the opercular valves are marked by corresponding letters and dashes.
1 c, Verruca Strömia, left hand scutum and tergum fixed, viewed from the under side.
1 d, Verruca Strömia, smooth var., reversed specimen, i. e., with the right hand scutum and tergum fixed and modified into part of the shell.
1 e, Verruca Strömia, shell seen from the under side; the right hand scutum and tergum (as in 1 d) being the fixed pair: the moveable scutum and tergum (S, T) are seen in the shade at the bottom of the shell, and their shape will be best understood by looking at fig. 1 f. The fixed scutum and tergum S′, T′, differ a little in shape, and in the form of their line of junction, from the same two valves (reversed) in fig. 1 c.
1 f, Verruca Strömia, moveable scutum and tergum, seen from the under side, taken from a specimen, in which (as in 1 d and e) the right hand scutum and tergum were the fixed pair.
2, Verruca Spengleri, scutum seen from the under side, showing the medial, prominent adductor ridge; taken from a specimen, in which the right hand scutum and tergum were fixed.
3 a, Verruca lævigata, scutum and tergum, external view of, from a specimen in which the left hand pair was fixed; 3 b, scutum and tergum, internal view of, from a specimen, in which the right hand pair was fixed.
4, Verruca prisca, scutum and tergum, external view of, from a specimen, in which left hand pair was fixed.
5, Verruca nexa, with the valves separated, the left hand scutum and tergum being the fixed and modified pair.
6, Portion of ribbed shell of a Venus, to which a Verruca Spengleri had been attached, showing the peculiar form of the excavation.
PLATE 22. ALCIPPE LAMPAS.
Fig. 1, Entire animal (female and two males) greatly magnified, being an unusually symmetrical specimen, partly copied from Mr. Hancock’s Plate (‘Annal. and Mag. Nat. Hist.’ ser. 2, vol. 4, Pl. VIII). H, horny disc and surface of attachment; a, projection formed by the lower end of the lip of the orifice leading into the sack; m, a pair of males, of their proper proportional sizes, attached in their ordinary position.
2, Entire animal, much distorted.
3, Small portion of a Fusus (copied from Mr. Hancock’s Plate), perforated by the Alcippe; the darker curved marks are the slit-like orifices, leading into the chambers; the latter are seen from the outside, owing to a difference of tint in the shell of the mollusc where worn thin over the chambers; they are represented by the fan-shaped shaded patches.
4, One of the orifices, leading into a chamber, much enlarged; a, the curved narrow end, which was open and used when the animal was young, but has since been closed externally by sand or shelly matter, and internally by the upward prolongation of the horny disc; b, rims of an inorganic, calcareous deposit, by which the narrow end of the orifice is kept of the due degree of narrowness.
5, Longitudinal section through the outer envelopes of a very symmetrical specimen, giving a lateral view of the included body.
a, point at the lower end of the orifice of the capitulum, leading into the sack.
b, end of adductor muscle.
c, mass of branching ovarian cæca, much developed and protuberant on the under side.
d, basal point of the quasi-peduncle, projecting beyond the level of the horny disc (H, H).
e, sack or open cavity: of the two branchiæ or ovigerous fræna, one has been removed with the outer envelopes, the other is hidden by the projection caused by the medial distended mass of the ovarian cæca.
e′, lateral line of junction of the body to the outer envelopes; which latter have been here cut through in removing the near half of the capitulum and peduncle.
f, notch separating the capitulum or upper part from the peduncle or lower part of the external covering: this notch varies much in depth.
g, the end (homologically the carinal end), of the orifice leading into the sack, where the cutting of the outer envelopes has commenced.
H H, horny disc, cut longitudinally down the middle.
h, first pair of cirri.
i, prosoma (homologically the second thoracic segment).
k, the thoracic segment, which would have borne the second pair of cirri, had such existed.
l, thoracic segment, which should have borne the third pair.
m, thoracic segment, which should have borne the fourth pair.
n, thoracic segment, very small, bearing the fifth pair of cirri.
n′, fifth pair of cirri, only one cirrus on the near side being represented.
o′, sixth cirrus, borne on the last thoracic segment, too small to be shown.
p, caudal appendages.
6, one side or lip of the orifice leading into the sack, greatly enlarged, seen on the inner side, formed of an inner membrane, b, (on which the long hairs and an S-like band of spines, too fine to be plainly represented, are placed), and an outer membrane c, studded with short, thick spines, the corium between these two membranes having been removed; a, projection at lower end of orifice; g, upper end of orifice, showing the point where the corresponding side or lip of the orifice has been cut away.
7, small portion of the external membrane, showing the star-shaped, hard, projecting points of chitine; but they are here placed too closely together.
8, front view of mouth, greatly enlarged, and with the gnathites rather unnaturally separated from each other; h, the first pair of cirri; in front, the outer maxillæ appear like a bilobed lower lip; the inner maxillæ (with their singular membranous swelling behind, see fig. 15), can be distinguished by their long apodemes or horny imbedded bars; behind are seen the one-toothed mandibles, with a swelling behind, probably representing the palpi; all above the mandibles consists of the immensely developed labrum, with the foreshortened ends of the row of long hairs on each side; the fold, or articulation, separating the mouth and body, is seen crossing above the basal ends of the apodemes of the maxillæ.
9, Lateral view of the coriaceous button or cushion, c′, on one corner of the upper segment, b, of the pedicel of the sixth cirrus; c, being the lower part of the lower segment of the one ramus of this same cirrus: the hooked hairs are rather distorted.
10, The same, viewed from the inner side.
11, Lateral view of the labrum, with the mandible, m, attached to it, which latter, from overhanging the œsophagus, shows the position of the mouth; h h, is the first cirrus on the near side; b, is the medial crest of labrum, on the side of which extends a long row of hairs; a a a, delicate membrane of side of body, attached to the margins of the labrum.
12, Diagram showing the probable manner in which the young Alcippe bores into the shell of molluscs; a, pupa attached by the antennæ to the outer surface of shell; b, outline of young Alcippe soon after its metamorphosis; the anterior or lower end has increased considerably in length, so as to project beyond the point whence the antennæ rise, and it has now penetrated the shell, being attached to the roof of its incipient chamber by its horny disc, represented by a thick black line; c, is the Alcippe after further growth, when it has succeeded in burying itself; the horny disc is now attached parallel to the surface of the shell; the horny disc of its former state, now lines the narrow end of the slit-like orifice leading into the shelly chamber: the above changes in position are supposed to have been effected quite gradually. The diagram, c, I may add, represents the position of the Alcippe for the rest of its life, the chamber being added to at both ends, sides, and bottom.
13, Lateral view of the posterior extremity of the thorax, much enlarged, with its articulated appendages represented only on one side; the four thoracic segments, l, m, n, o, correspond with those represented in fig. 5. In one monstrous specimen, segment n, bore a single cirrus. The posterior thoracic segment, o, bearing the sixth pair of cirri, o′, is very small and obscure, and can be seen only by separating the fifth and sixth pairs of cirri; or by longitudinally bisecting the thorax, and viewing the inner side; n′, fifth cirrus; a, lower segment, b, upper segment of pedicel; c, lower, and d, upper segment of the one ramus, the other ramus being represented by the coriaceous boss c′; o′, sixth cirrus, with similar segments; p, caudal appendage.
14, First cirrus.
15, Maxillæ, with the lower end of the apodeme cut off, showing the curious membranous swelling on the side towards the mandible.
PLATE 23. Genera—ALCIPPE AND CRYPTOPHIALUS.
ALCIPPE LAMPAS.
Fig. 16, Pupa of male Alcippe lampas, viewed laterally; a, antennæ, c′, eyes attached to the apodemes; above these the single eye of the mature male may be distinguished.
17, Abdomen of the same; p, posterior end of thorax; q, abdomen; r, caudal appendages.
18, Male of Alcippe lampas immediately after the metamorphosis, the ventral surface being uppermost, but the specimen has been in some way distorted, as the lobe (i) ought to project on the opposite side; a, antennæ of the pupa; g, h, lateral lobes; internal organs not yet formed; orifice at upper end (i) not visible; scale same as for the pupa, fig. 16.
19, Male of Alcippe lampas, when fully mature; scale same as in last figure (18) and as in fig. 16.
a, antennæ of pupa.
b, vesicula seminalis.
c, eye, (seen in fig. 16 above the eyes of the pupa, c′.)
d, testis.
e, lower transverse muscle.
f, upper transverse muscle.
g, h, lateral lobes of the external covering, answering to the sides of the peduncle of the female.
i, terminal lobe on the ventral side of the orifice, probably corresponding with a in fig. 1, Pl. 22.
k, orifice of the tubular sack.
l, oblique muscles on the ventral side of the sack.
m, probosciformed penis, shown exserted; m′ portion within the tubular sack.
CRYPTOPHIALUS MINUTUS.
Fig. 1, Cryptophialus minutus (female with an attached male) viewed laterally, but with the disc (H) rather turned towards the beholder, much enlarged; a, orifice leading into the sack; H, thin horny disc by which the animal is attached within its cavity; H′, upper free worn edge of the disc; z, male attached in its usual position to the edge of the disc of the female.
2, Cryptophialus minutus, natural size, within a half-inch circle; this represents the largest specimen which I have ever seen.
3, Half the orifice, with a large portion of the external membrane and of the membrane lining the sack.
a, a, dentated horny rim of orifice.
b, b, external membrane, with the underlying corium or true skin removed.
b′, a horny bar, expanding at its lower end into a toothed plate, and at the upper end connected with the horny rim round the orifice.
c, c, membrane lining the sack.
c′, horny bar by which this membrane is strengthened.
c′′, thickened membrane, or bar, expanding into fibrous sheets for the attachment of a muscle.
d, delicate lateral lip, within the outer dentated horny rim.
4, Orifice of sack, cut off, widely open, viewed from above; a, horny dentated rim; b′, top of horny bar, where united to the rim; d, inner lateral lip folded backward; d′, lip, with coarser hairs, at the carinal end of the orifice.
5, Animal with the outer tunics removed, viewed laterally.
a, dentated horny rim of orifice, continuous with
b, outer membrane, here cut off.
c, inner membrane of sack, continuous with
c, c, the reflexed membrane of the body, by which the body is united to the disc and outer envelopes.
e, lancet-shaped labrum.
e′, projection behind the labrum.
f, palpi.
g, outer maxillæ, between which and the palpi lie the inner maxillæ and mandibles; these latter are rather exaggerated in size.
h, first maxilliped, in a rudimentary condition, close above which is the articulation separating the whole mouth (o) from the first (1) segment of the body.
i, k, tapering appendages springing from the second and third segments of the body.
l, pedicels of the three pairs of abdominal cirri.
m, cirri, three pairs of.
o, mouth, of great size, formed by the confluence of the lower segments of the gnathites.
1, first segment of body, homologically the last or seventh cephalic segment.
2, second segment of body, homologically the first thoracic segment.
3, third segment of body, homologically the second thoracic segment.
4, fourth segment of body, homologically the third thoracic segment.
5, fifth segment of body, homologically the fourth thoracic segment.
6, sixth segment of body, homologically the fifth thoracic segment.
7, seventh segment of body, homologically the sixth thoracic segment.
8, eighth segment of the body, homologically the seventh thoracic segment.
6, Front of mouth; g, outer maxillæ; g′, an articulation separating the mouth from the membrane of the first segment of the body; h, first pair of maxillipeds; whole figure on same scale with the labrum, fig. 9.
7, Maxillæ, drawn on thrice the scale as the outer maxillæ; a, apodeme.
8, Mandibles, drawn on thrice the scale as the outer maxillæ.
9, Labrum, on same scale with the outer maxillæ, fig. 6, and one third of the scale of the mandibles and inner maxillæ; e, labrum; f, palpi.
PLATE 24. Genera—CRYPTOPHIALUS AND PROTEOLEPAS.
CRYPTOPHIALUS MINUTUS.
Fig. 10, Lower enlarged end of œsophagus, where entering the stomach, viewed from one of the sides bearing the discs of teeth; a, upper cut off end of œsophagus; b, the lower end and natural opening; c, thickened rim, having a somewhat beaded structure.
11, The same; diagram giving a transverse section of the above in the line of the discs of teeth; c c c c, four thickened beaded edges; e e, two other but narrower and less prominent beaded edges; d d, discs of teeth; f, rows of fine bristles; the almost double row of bristles on each side under (d) is not of course seen in this section.
12, Lower end of œsophagus viewed from a position at right angles to that in fig. 10; or from the side e, of the diagram, fig. 11; the two discs of teeth are consequently shown in profile; a, upper cut off end of œsophagus; b, lower natural end; c, c, thickened edges; e, narrower thickened edge, projecting towards the beholder; d, disc of teeth seen in profile.
13, Portion of one of the cirri; a, lower segment of pedicel; b, upper segment, supporting the two rami.
14, Segments of one of the rami much enlarged; a, thickened shield-like portion of membrane.
15, Ovum, (thirty-five times the natural size.)
16, Egg-like larva in the first stage, on same scale.
17,””in the second stage, on same scale.
18, Larva in the last or pupal stage, on four times the scale of fig. 15-17; a, antennæ; b, apodeme and eyes; c, abdominal bristles. A male would have been developed from this pupa.
19, Male on same scale as the pupa, fig. 18; a, three terminal segments of the antennæ of the pupa; d, orifice of the sack.
PROTEOLEPAS BIVINCTA.
Fig. 1, Antenna of the pupa (three terminal segments of), with a portion of one of the two threads, enclosing the cement-ducts, by which the body of the Proteolepas is attached; the upper portion of the thread, and the adjoining part of the body, are represented in section.
a, part of the great mass of cellular matter within the ovarian sack, in process of development into ova, and changing its character as soon as it enters the tube or cement-duct.
b, membrane forming the ovarian sack and the cement-ducts, the latter enclosed within the threads of attachment.
c, corium lining the outer membrane of the body, and the upper part of the threads.
d, outer membrane of body.
e,””becoming suddenly thicker where forming the outer membrane of the thread.
e′, outer membrane of the thread in the lower part, here not shown in section.
f, main or second segment of the pupal antenna, the basal segment having, as in all cases, been moulted, with the carapace of the pupa.
g, disc-segment, apparently with a small orifice for the issuing of the cement.
h, terminal segment with the shorter spines broken off.
2, Compounded mandibular organ, sketched by the camera; a, supposed mandible; b, perhaps portion of the mandible; c, maxilla; d, ligamentous fibres giving attachment to muscles.
3, Mouth seen from the ventral side, sketched by the camera; r, articulation separating the mouth from the body; c, compounded mandibular organ; d, palpus, united to the opposite palpus and to the crest of the labrum; the latter forming the back of the hollow in which the compound mandibles work.
4, Diagram of the mouth of an ordinary cirripede, seen from above; a, outer maxilla; b, maxilla; c, mandible; d, labrum.
5, Diagram, illustrating the supposed changes in position of the gnathites in Proteolepas, causing them to stand back to back; a, outer maxilla; b, maxilla; c, mandibles; d, labrum.
PLATE 25. Genera—PROTEOLEPAS AND BALANUS.
PROTEOLEPAS BIVINCTA.
Fig. 6, Proteolepas bivincta: diagram, showing the probable position of the young animal, just before its metamorphosis, within the carapace of the supposed pupa; a, caudal appendages; b, six pairs of natatory thoracic legs; c, mouth, no doubt closed and functionless, as in other pupæ; g, threads of attachment, with cement-ducts in process of formation; h, antennæ.
7, Proteolepas bivincta, magnified about twenty-six times.
m, mouth, the summit being formed of the labrum and palpi joined.
1c, first segment of body; homologically the seventh or last cephalic segment.
2t to 8t, second to eighth segment of body; homologically, first to seventh thoracic segments.
9a to 11a, ninth to eleventh segment of body; homologically, three segments of abdomen.
d′, three muscles attached on each side to the labrum, and running to the gnathites.
e e, great ovarian sack.
f, true ovaria.
g, threads of attachment.
h, three terminal segments of the antennæ of the pupa.
i, vesicula seminalis.
k, papilla representing the penis.
Fig. 1, Balanus tintinnabulum: an enlarged longitudinal section through the shell and sack, with the right-hand scutum and tergum and right-hand half of shell and basis removed, exhibiting the body of the animal not in section. The cirri are exhibited only on one side.
A, A, orifice of shell, within which lies the operculum formed by a pair of scuta (S), and pair of terga (T).
B, basis (homologically the anterior end of the shell).
K, carina of shell (or dorsal valve or compartment of shell).
K′, sheath of carina.
L, lateral compartment of shell. The carino-lateral compartment is hidden by the scutum and tergum.
R, rostrum of shell (or ventral valve or compartment of shell).
R′, sheath of rostrum.
O, O, opercular membrane, connecting the opercular valves with the overhanging basal edge of the sheath.
S, scutum.
T, tergum.
a, adductor scutorum muscle, with the scutum on the near side removed.
b, the whole space enclosed by a broken sinuous line, round a and b, shows the cut surface of attachment to the near scutum, which has been removed.
b′, lower muscle, on the near side, running from near the basal edge of the scutum to near the basal margin of the labrum (e). Above this are three other muscles (all on the near side), running to the membrane between the labrum and adductor muscle.
c, prosoma, including the main portion of the stomach and thickened ends of the vesiculæ seminales: homologically this is formed by the development of the second thoracic segment, which carries the first pair of cirri; and possibly, in part, by the antecedent segment, i. e. the first thoracic segment.
c′, thorax, extending from the prosoma to the posterior end of the body: the letter (c′) stands on the segment supporting the third cirrus; homologically, this segment is the fourth thoracic.
d′, orifice of the acoustic sack, above which is the basal articulation of the first cirrus.
e, labrum, forming the back (i. e. anterior end) of the mouth, with the transverse palpi obscurely seen on the summit.
f, sack in which the animal lies, with the tunic lining it, continuous with that investing the prosoma (c), and lining the under sides of both opercular valves, but cut off round (b) and (a) by the removal of the near scutum. The branchia on the further side, which occupies the position represented at fig. 3, is covered by the body of the animal.
g g, ovarian, inosculating cæca, branching from the simple duct (of which the near one of the pair is represented), leading to the ovaria (not represented) within the body.
h, rostral depressor muscle of the scutum: the lateral depressor muscle of the scutum is hidden by the body and by the membranes of the sack.
i, carinal depressor muscle of the tergum.
z, antennæ (three terminal segments) of the pupa; I distinctly saw these in this species, but they are here represented considerably too large, even on the supposition that a young shell had been drawn, and magnified about twelve times.
2, Testes of Balanus perforatus, greatly magnified.
3, Branchia of Bal. tintinnabulum, on the same scale as in fig. 1, and in its natural position. This drawing was made by lifting up the body in fig. 1; the organ being thus completely exposed over its whole interior surface; a is the basal end of the spur of the tergum.
PLATE 26. STRUCTURE OF THE MOUTH AND THORAX.
N.B.—The same letters of reference are used for the parts of the mouth throughout this plate. All the organs here represented have been cleaned by boiling in potash, and consist exclusively of the external membrane.
Fig. 1, Mouth of Balanus perforatus, viewed from vertically above, with the first pair of cirri x x in their proper position, cut off close above their basal articulations.
a, outer maxilla; a′, ditto, cut closely off.
b, maxilla.
c, mandibles.
d, palpus; d′ ditto, cut closely off.
e, labrum, crest of.
x x, first pair of cirri, cut off.
2, Supra-œsophageal cavity of the mouth of Balanus improvisus, torn open, with the palpi, mandibles, and maxillæ removed, exhibiting the inner face of the labrum, laid flat, and the inner faces of the outer maxillæ; scale as in fig. 1.
a, outer maxillæ; a′′, inner and lower lobe of ditto.
d′, point of attachment to the torn-off palpus.
e, labrum, crest off; e′, central notch, with graduated teeth on both sides.
f, triangular thickened portion of the inner fold of the labrum; f′, rib or bar of membrane, thickened to support the surrounding very thin membrane of the supra-œsophageal cavity.
g, opening of the œsophagus.
h, forked bar of thickened membrane, for same purpose as f′.
3, Mouth of Coronula balænaris, divided vertically in a transverse line, with the outer and inner maxillæ and mandible on the left side removed, with the labrum, the other mandible and both palpi viewed on the inside, and with the œsophagus adherent in its proper position.
c, Mandible, upper free segment; c1, second or middle segment; c2, supposed third or basal segment, forming the basal margin of the mouth, but not separated by any articulation from the labrum.
d d, palpi; d′, aperture, through which the inside of this palpus can be seen, caused by the mandible having been cut off; the membrane on the under side of this aperture is thickened, and affords the chief support to the palpus; d′′, thin membrane, apparently part of the palpus, connecting the attached basal end of the palpus to the externo-lateral surface of the mandible.
e′, central notch in the crest of the labrum; e′′ e′′, basal margin of the labrum, to which the membrane of the body is joined.
f, thickened portion of membrane, part of the inner fold of the labrum, corresponding with f in fig. 2.
g, orifice of the œsophagus, with the front part of the supra-œsophageal cavity cut away; g′, lower, expanded, or bell-shaped, end of the œsophagus, in its natural condition.
i, k, concavities for the attachment of muscles running to the mandibles.
m, cut off edge of membrane forming the side of the mouth, which cut edge can be followed up above the aperture d′, where the upper basal end of the palpus has been cut off, and so onwards by g, to the mandible on the opposite side of the mouth.
4, Mouth of Coronula balænaris, viewed from the outside, in front, with the inner maxilla, mandible, and palpus on the left side of the figure, and nearly the whole labrum, and the greater part of the palpus on the right side, all cut away. The maxilla, mandible, and basal portion of the palpus on the right hand, are pulled out of their proper positions; for the toothed edge of the mandible ought to have stood higher, and nearly in a line between and behind the outer maxillæ, and then the basal margin e′′ of the lateral portion of the labrum would be raised, and curling round, would stand nearly where the letter b′ is now placed.
a a, outer maxilla, upper free lobe; a′′, lower and inner free lobe; a1, supposed second or middle segment; a2, supposed third or basal segment; a′′′, basal articulation of mouth, separating it from the ventral surface of the thorax.
b, inner maxilla; b′, apodeme of do.
c, mandible, upper free segment; c1, second segment; c2, third and basal segment, but not separated by an articulation from the labrum.
d, palpus; d′′, membrane uniting the basal end of the palpus, where attached to the labrum, to the side of the mandible.
e′′, basal margin of the labrum, on one side, displaced and pulled down.
n, orifice of the olfactory pouch.
5, Balanus amaryllis: mandible, upper free segment, seen from the side that faces the labrum; p, an arched line, where the thickened membrane of the upper free part terminates, and is united by thin membrane to the near side of the palpus; q, ligamentous bands for the attachment of muscles.
6, Balanus amaryllis: palpus, on the same scale as the mandible, fig. 5, seen from the outside, so that the further or under face is the side which, towards the right hand, is united to the near face of the mandible, fig. 5; r, long bristles, springing from a protuberance near the extremity; these bristles, in many species, form a long single row, parallel to the basal margin; s, upper row of shorter bristles; t, row of very short bristles, arising from the further side and curling over the crest of the labrum.
7, Balanus amaryllis: maxilla on twice the scale of the mandible and palpus; b, upper free segment; b′, apodeme; b1, thickened portion of membrane, perhaps answering to the second segment of the mandibles; b2, thin membrane, extending down to the basal edge of the mouth, possibly answering to the basal segment of the mandibles; or perhaps the thickened membrane forming the protuberance c2 in fig. 3, may be considered as the basal segment of the maxillæ.
u, step-formed projection at lower angle of maxilla.
8, Thorax of Coronula diadema: outer membrane of the five posterior segments laid almost flat, and viewed externally as a transparent object.
2 to 6, the second to the sixth cirrus, cut off a little above their basal articulations.
a, basal curved end of the probosciformed penis.
b, anus; b′, the membrane surrounding the anus, probably consisting of a rudiment of the abdomen.
c, rectum, seen through on the under side.
d, basal articulation of the sixth cirrus; d′, do. of the fifth cirrus; d2, do. of the second cirrus.
e e′, posterior thoracic segment, carrying the sixth pair of cirri; the dorso-lateral portion e is separated, in this one segment, from the corresponding portion e′ by a narrow slip of thinner membrane, which may be a part of the abdomen let in.
e2 e2, thoracic segment, supporting the second pair of cirri.
f, f3, folds or articulations between the adjoining segments.
g, swollen, punctured portions of membrane, not differing homologically from the rest of the segments.
h, posterior portion of the prosoma, or the specially enlarged part of the thorax; it carries the first pair of cirri; homologically h forms part of the second segment of the thorax of the archetype Crustacean.
PLATE 27. NERVOUS SYSTEM AND SENSES.
Fig. 1, Nervous system of Coronula diadema, seen from the ventral surface.
A, infra-œsophageal ganglion; two pairs of rather small nerves, arising from the dorsal surface, cannot be here shown.
B, supra-œsophageal ganglion, double.
C, ophthalmic ganglion, single.
D D, eyes, as believed to exist.
a, three pairs of nerves, running to the gnathites and olfactory pouches; a′, nerve rising from the collar, running towards the mandibles.
b, single medial nerve, running to the great transverse muscle, extending across the upper part of the stomach.
c, collar-nerve or chord, uniting the infra- and supra-œsophageal ganglions.
d, great splanchnic nerve, here spread laterally out, but properly running along the sides of the upper part of the prosoma, and therefore under the collar-nerve; d′, plexus by which this nerve is connected with the supra-splanchnic nerve, e.
e, supra-splanchnic nerve, rising from the collar, almost in contact with the supra-œsophageal ganglion; e′, small nerve rising from the end of the supra-œsophageal ganglion, and running to the adductor and surrounding muscles.
f, f, pair of great nerves (antennular), distributed over the sack and shell.
g, chord (in appearance single), uniting the supra-œsophageal ganglion with the first (C), or ophthalmic ganglion.
h, small medial nerve, running to near the adductor muscle.
i, nerve supposed to run from the ophthalmic ganglion to the eye.
k, small nerve, rising from the main ganglion (A), between r1 and r2, or the nerves running to the first and second pairs of cirri.
œ, position of the œsophagus.
r1 nerve entering the first cirrus.
r2, r3, r4, r5, r6, nerves entering the five succeeding pairs of cirri.
s, nerve entering the probosciformed penis.
2, nervous system of Balanus tintinnabulum; letters of reference as in fig. 1.
3, acoustic sack of Balanus tintinnabulum.
4,””Coronula diadema.
5, eye of Balanus tintinnabulum; i, nerve coming from the ophthalmic ganglion; D, eye itself.
PLATE 28. CEMENTING APPARATUS.
Fig. 1 a, Basal membrane, with the cementing apparatus, of Coronula balænaris; a small portion of the parietal membrane, p p p, which coats the folded shelly walls, is left adherent to the basal membrane.
b, the circumferential slip (shaded more darkly than the rest to catch the eye), separating the basal from the parietal membrane.
c′ c′, slips of basal membrane, formed at each period of growth, and overlapping each other.
s s s s s s, the six sutures in the walls, separating the six compartments, of which—
A is the basal margin of the rostrum,
C C that of the lateral compartments,
D D that of the carino-lateral compartments, and
E that of the carina.
r, r, rays or spokes of membrane, prolonged from the circumferential slip, and running under the trebly folded wall of each compartment, but here cut off; a similar ray should run under each line of suture (s). These rays, at their extremities, expand transversely; and the shape and length of the rays may be judged of from the basal outline of the folded walls given in Pl. 16, fig. 5.
The two cement-ducts, proceeding from each cement-gland, debouch opposite the middle folds of the lateral (C C) and carino-lateral (D D) compartments. The layers of cement have been removed. N.B. There is one considerable error in this figure, the two main trunks, connecting the cement-glands, and meeting at the centre, have been represented as forming a straight line, but in fact they form a very open angle, as is correctly shown in fig. 1 c.
1 b, Diagram, representing a vertical section through a portion of the basal and parietal membranes, with the thickness of the membrane enormously exaggerated.
z z z, layers of cement, which, if the section had been made in the line of the cement-ducts, would have been seen proceeding out of these ducts, as is represented at (t), where the section is supposed to have taken the above course.
c′ c′, the slips of basal membrane.
b, the circumferential slip; beneath this the coarsely dotted layer represents the cement, lately excreted, and before it has acquired its proper transparent structureless character, elsewhere represented by fine dots.
p, membrane externally coating the walls of the shell.
t, cement-ducts opening beneath the basal membrane.
1 c, The central portion of fig. 1 a, considerably magnified.
c′ c′, slips of the basal membrane; but the shell, when these were formed, was so young that the walls had not acquired their folded structure; in the centre the prehensile antennæ of the pupa may be obscurely seen.
f, the main cement-trunk, connecting the cement-glands.
h, a cement-gland, from which two cement-ducts proceed.
a a, cement-ducts (cut off), leading to opposite the middle fold of the carino-lateral compartment.
b b, cement-ducts (cut off), leading to opposite the middle fold of the lateral compartment.
a′ b′, a pair of cement-ducts, with their orifices opening on the under side of one of the slips of basal membrane (c′), at a point which once was opposite the middle of the carino-lateral and lateral compartments. The orifices of the other ducts, towards the centre, may be seen forming straight lines.
2, Cement-ducts and one cement-gland of Chelonobia patula, represented without the basal membrane, to which they adhere: f, f, main cement-trunk; g, enlarged portion; h, gland; a, b, the two ducts proceeding from this gland, and bifurcating several times before debouching on the under side of the basal membrane. Several other cement-ducts, proceeding from other glands, are represented just as they appeared under the microscope.
3, Cement-ducts and glands of Tubicinella trachealis, represented without the basal membrane to which they adhered: (f) (f), main cement-trunk, connecting the several glands; h, cement-gland; a, cement-duct, with a singular loop (a′) having two projections or rudimentary branches; b, spur or rudiment of a second cement-duct; c, third cement-duct.
4 a, Chain of cement-glands of Balanus tintinnabulum, with all the ducts removed, excepting those proceeding from the last formed gland, which latter correspond in age with the last-formed zone of the shelly basis; the whole of the basis having been removed by acid.
f, main cement-trunk connecting the glands.
gh, last-formed cement-gland.
k, t, two cement-ducts, proceeding from a great common duct; one of these bifurcates at (t), and one branch joins at (t′) the corresponding branch from the corresponding gland.
i i i, circumferential duct, into which the ducts k, k, t, t, t′ all enter.
i′ i′, branches proceeding from the circumferential duct, which branch and sub-branch till they form a sheet (z z) of cement-tissue on the outside of the basis of the shell.
4 b, two cement-glands of Bal. tintinnabulum (this figure, to match with 4 a, ought to have stood upside down), taken from near the centre of the basis, greatly enlarged; (f f), main trunk; (g), enlarged portion of the trunk; (h), gland; k, t, two cement-ducts proceeding from a common point, one of them (t) bifurcates, and gives off a rudimentary branch, t′; m, a spur, or rudimentary duct. The gland, h, has been pushed on one side, it ought to lie over the enlarged portion (g). There is a considerable difference between these two glands and that (gh) represented in fig. 4 a; the neck of the gland in the latter being elongated into a great common duct, and the spur or rudimentary duct (m) being absent.
PLATE 29. CIRRI AND LARVÆ, FIRST STAGES.
Fig. 1, Sixth cirrus of Balanus amphitrite (var. cirratus), showing the muscles.
a, b, flexor and extensor muscles, moving the upper segment (i to k) of the pedicel.
c and d, flexor and extensor muscles, apparently moving the lower segments of both rami, as a whole; the lower articulations in these rami being confluent.
e and f, flexor and extensor muscles extending up both rami (those only in the near ramus being figured) to their tips.
g g, flexors of the separate segments in both rami.
h, basal articulation of lower segment of the pedicel.
i, upper articulation of lower segment of the pedicel.
k, upper articulation of upper segment of pedicel.
2, Fourth cirrus of Acasta sulcata.
i, upper articulation of the lower segment of pedicel.}These two letters apply to all the figures, 1 to 6.
k, upper articulation of the upper segment of pedicel.}
l, curved teeth on the pedicel.
m,””on the segments of the anterior ramus.
3, Third cirrus of Chthamalus antennatus.
4, Second cirrus of Balanus perforatus, viewed exteriorly and laterally.
5, Third cirrus of Xenobalanus globicipitis.
6, Sixth”””
7, Spermatozoa (copied from Mr. C. Spence Bate, in ‘Annals and Mag. of Natural History’ (S. 2), vol. viii, Pl. VIII).
a, of Verruca Strömia, in an early condition.
b, of Balanus balanoides, more mature.
c, of Balanus perforatus, apparently mature.
8, Larva of Scalpellum vulgare, immediately after coming out of the egg, seen on the ventral surface (letters of reference given below).
9, Larva of Balanus balanoides, immediately after coming out of the egg, seen on the ventral surface, copied from Mr. C. Spence Bate’s drawing in ‘Annals and Magazine of Natural History’ (S. 2), vol. viii, Plate VI, fig. 1 (letters of reference given below).
10, Larva of Chthamalus stellatus, after the first moult, but during the first stage, seen on the ventral surface, copied; with some alterations, from Mr. C. Spence Bate’s drawing in ‘Annals and Magazine of Natural History’ (2 Ser.), vol. viii, Plate VIII, fig. 13.
(The following letters apply to above figs. 8, 9, 10.)
a, eye.
b, first pair of antennæ, not observed in fig. 9.
b′, the same antennæ, as yet encased (in fig. 8) within small horns.
c, horns, including the second pair of antennæ.
d, mouth, probosciformed: in fig. 8, the specimen having been acted on by potash, the œsophagus can be seen within, with the orifice beneath the swelling, which latter perhaps answers to the labrum.
e, first, uniramous natatory leg (homologically the second thoracic limb).
f g, second and third, biramous natatory legs (homologically the third and fourth thoracic limbs.)
h, posterior point of carapace.
i, forked terminal projection of the body or abdomen.
l, second forked projection.
m, two sharp points, apparently representing a third forked projection.
n, a rounded swelling, apparently lying between the carapace and the supposed abdomen, and believed to form the anus.
PLATE 30. LARVÆ OF LEPAS: SECOND AND LAST STAGES OF DEVELOPMENT.
Fig. 1, Larva of Lepas in the second stage of development; a, supposed antennæ (second pair); m, mouth; c, three pairs of legs. (Copied from Burmeister’s ‘Naturgeschichte der Rankenfüsser,’ Tab. 1, fig. 3.)
2, Lepas australis: pupa or larva (2 a, of natural size) in the last stage of development, with the young cirripede in its natural position, obscurely seen within,—the specimen having been treated with caustic potash, and so rendered transparent,—viewed laterally and greatly enlarged. Scarcely more than the outline of the shell or carapace is represented. The darkly shaded part to the left represents the extent of the sack of the pupa, or the cavity occupied by the thorax, with its limbs.
a, both antennæ, adhering by their discs to a piece of wood.
b, dorsal surface of the shell or carapace; and immediately underneath this letter is the point of reflection of the membrane investing the thorax, so as to line the sack of the pupa.
b′, is the posterior end of the animal, and of the orifice on the ventral surface, through which the legs are protruded.
c, six pairs of natatory legs.
d, pair of caudal appendages, seated on a minute abdomen.
m, mouth, from which the œsophagus can be seen running into the stomach, the latter having two dark cæca; the stomach sweeps round in the pupa to the abdomen, near b′; but in the young included cirripede, only as far as the letter (b), where the bases of the posterior pair of cirri and the anus lie.
n, apodemes, supporting the eyes, produced deeply inwards from the eye-bearing segment (N, in fig. 4) of the antennæ.
s, bottom of sack of the young cirripede immediately after its metamorphosis; it extends as far as s′. (See s, in fig. 3.)
t, gut-formed cement-gland (or incipient ovaria), seen on the near side of the animal, whence a cement-duct, t′, runs into the near antenna.
u, internal and anterior part of the pupa, filled with pulpy, oily matter, together with the incipient muscles of the peduncle; when stretched out it forms the peduncle of the young cirripede. See u′, in fig. 3.
x, bases of the pedicels of the cirri of the young included cirripede.
2 a, Pupa of Lepas australis of natural average size, within a half-inch wide.
3, Young cirripede (on a smaller scale than Fig. 2), immediately after the exuviation of the bivalve-like pupal carapace, the basal segments of the antennæ, the eye-apodemes and eyes. The young cirripede has just assumed its proper position at nearly right angles to what it held whilst packed within the pupa,—this change of position having been effected by the opening out or stretching of the deep fold of membrane (see n, in fig. 2) formed over the eye-apodemes and eyes, previous to the act of exuviation.
a, the three terminal segments of the antennæ of the pupa, still remaining cemented, in the same position as before, to the same piece of wood: the basal, or eye-bearing segment (N, in fig. 4), has been moulted with the pupal carapace.
c, d, legs and caudal appendages of the pupa, not as yet moulted, but quite functionless; the external membrane of the thorax, and that lining the sack of the pupa, are, likewise, as yet retained, but soon will be cast off.
s, bottom of the sack of the young cirripede, which can now be easily distinguished.
u′, the peduncle.
x, y, z, primordial valves, composed of chitine: x, being the scutum; y, the tergum; z, the carina.
3 a, small portion of one of the primordial, non-calcified valves, much magnified.
4, ventral surface of pupa; on the same scale, and in the same semi-transparent condition as in fig. 2.
a, antennæ.
b, limit of sack on the sides in the ventral or lower half of the pupa.
b′, posterior end of the carapace.
c, d, bristles of the natatory legs and of the caudal appendages, protruded through the orifice of the carapace.
e, orifice of the acoustic sacks.
m, mouth, with the œsophagus attached to it, obscurely seen through the carapace; the stomach having been removed.
n, apodemes supporting the eyes.
N, the eye-bearing or basal segments of the antennæ.
o, the second or main segment of the antennæ.
p, the third or disc segment of the antennæ.
v, the fourth or terminal segment of the antennæ.
W, ventral surface, bordered by the edges of the carapace; the letter stands near the extremity of the œsophagus.
5, First pair of natatory legs: f, lower segment of pedicel; g, upper segment of pedicel; h, lower segment of ramus; i, upper segment of ramus; k, outer ramus; l, inner ramus of same leg; r, sternal surface between the first and second pairs of legs, with singular thickened ridges and folds.
6, Abdomen with two caudal appendages: 1, first abdominal segment, attached to the posterior thoracic segment; 2, second abdominal segment; 3, third or last abdominal segment; h, lower segment; i, upper segment of caudal appendage.
7, Transverse section of the pupa, close to the eye-apodemes; these being made to stand more upright than in fig. 2. The internal organs of the animal have all been removed.
a a a′, section of carapace; from a to a′, on the lower side, forms the ventral surface, with three longitudinal furrows, here in some degree opened out.
c, crest of thick membrane on each side, forming the sides of the lateral furrows.
N, the posterior margin of the eye-bearing segment (see fig. 4) of the antennæ; the edges of which are hardened and thickened, and are produced inwards, forming
n, the apodemes, to which are attached the (n′) great compound eyes.
8, Terminal portion of an antenna, greatly magnified, seen from above.
o, part of the second or main segment; an oblique line shows a line of separation of the upper thinner and lower thicker membrane; o′, single spine borne at this segment.
p, disc-segment, bearing seven spines; p′, an irregular border of the cement-tissue, believed to have debouched through the spoke-like minute tubes seen on the disc.
v, terminal segment, projecting almost rectangularly outwards; v′, most delicate tube or ribbon, believed to consist of cement-tissue.