Note 176 — {137} CHAPTER VIII

We add some notices of a few of the most important.

1. Terebratula.—A specimen considerably resembling the T. subundata of Sowerby, in the undulated line of the edges of the valves; but it is a much more depressed shell, and of a much less rounded form.

In the young state, the undulation of the edge is not very distinct; but this character increases with age, so that in the young state, it appears like a totally different species from the adult.

2. In the same rock are very numerous arquated spines, like ribs of fish, some of them 1½ inches long.

3. A fragment of a terebratula or productus, imbedded, with very long spines, which may possibly be the same with the above.

4. A specimen, being a mass of comminuted fragments of shells, amongst which are only recognizable a few segments of the column of the encrinus, and minute turretted univalves of five whirls, which resemble turritella, and are about one-twentieth of an inch long.

5. Millepora cylindrica, Say.—Branched, cylindric; pores very regular, alternate, oval, placed nearer to each other than the length of their own transverse diameters, and resembling those of an alveolite.

Diameter, about one-tenth of an inch.

6. Segments of the column of encrinus of authors, of a pentangular form.

7. Ossiculæ of the body of a crinoid animal of the analogous species to No. 21.

8. Fragment of Perna?

9. A mass of argillaceous sandstone, containing spines of a Linnæan echinus, belonging probably to the genus cidarites of Lamarck. Of these spines some are elongate-conic, others slightly fusiform, obtuse and slightly dilated near the tip, both are armed with short asperities throughout their length. They resemble in some degree those of the cidarites pistillaris of Lamarck, but they are smaller, less fusiform, and the asperities are not prominent.

In the same mass are segments of encrinus, and fragments of the retepore.

10. Retepore, much resembling the milleporites flustriformis of Martin, Petrif. Derbi. pl. 43. fig. 1 and 2., but the alveoles in our specimens are rather smaller.

11. Millepora cylindrica, Say.—Of the diameter of half an inch.

12. Productus subserratus, Say.—Shell transverse, convex valve semicircular, destitute of asperities or striæ, longitudinally indented in the middle; line of the hinge rectilinear, half as long again as the length of the shell, with three or four spines or serratures on each side towards the angle; umbo not prominent; the beak hardly prominent beyond the line of the hinge. Length, more than three-tenths; breadth, more than half an inch. A large specimen was four-fifths of an inch wide.

If we except the beak, the outline of this shell, as respects the hinge margin and the sides, considerably resembles that of P. spinulosus of Sowerby, but the base is far more obtusely rounded, and it is a shorter shell comparatively with its width. The serratures are very often broken off. The curvature of the sides does not in the slightest degree project beyond the angles of the hinge line.

13. An imperfect cast, very like the terebratula subundata of Sowerby, and of equal magnitude.

14. Pentagonal ossiculæ of the trunk of encrinus of authors, which in outline may be compared to figs. 61 and 62, of plate 13. vol. 2. of Parkinson's Organic Remains, but their surfaces do not now exhibit any sculpture.

15. Many of these shells exhibit the most unequivocal evidences of having been in a plastic state, at some period or other, since their deposition in their present situations. The fine striæ of a productus lineolatus, are so interlaced on the middle of a valve of one of our specimens, as at once to convince every observer of the shell having been thus partially dissolved, and when in this state to have been gently rubbed by some other body, in two directions proceeding obliquely to the same point, so as to throw the striæ in that part entirely out of their proper longitudinal direction. It is very common to find shells unnaturally flattened, or compressed in various ways and degrees, often without any fracture in the shell or cast; a circumstance which certainly could never happen to the shell, unless it was in a plastic state, or in a state of partial solution.

16. A specimen of carbonate of lime, on its surface a mass of sub-parallel tubes, connected by short lateral processes. The whole much resembles, and is probably congeneric with the erismatholithus tubiporites (catenatus) of Martin's Petrif. Derbi. t. 42. fig. 2., but the connecting processes of the tubes are much shorter than they are represented in that figure; but it corresponds much more exactly with the tubiporite, figured by Parkinson in his Organic Remains, vol. 2. pl. 1. f. 1., and may with great propriety form a new genus, the type of which will be the tubipora strues of Lin.

The genus is probably allied to favosites and tubipora.

17. Trilobus.—The abdomen of a species of this singular genus frequently occurs in the sandstone of the Missouri; near Engineer Cantonment they were very common. The largest was rather more than one inch long, by about one and three-tenths inches in breadth at base; but the more general length is about three-fourths of an inch. The tergum or intermediate lobe is narrow, being not more than two-thirds of the width of the flanks, and much more convex than those parts.

But a single specimen occurred, which we can, without any doubt, consider as the thorax of a trilobus; but whether or not it appertains to the same species with the above, or to some other of which we have no other fragment, we are at a loss to determine. Like the above-mentioned abdomen, it is distinct from any that we have seen figures of. It is of a narrow lunate form, highly convex, the disk destitute of sculpture, and the eyes prominent.

18. Many imperfect casts of two different kinds of bivalve shells occur near Engineer Cantonment, of which one may possibly have been a cardita.

19. Tooth of a squalus, which seems to approach nearest to those of Sq. maximus, by its compressed conic form.

Greatest length 2¹⁄₁₀ inches.

Thickness more than ²⁄₅ of an inch.

The sides are rounded, without any appearance of serratures; thickened near the tip, and more compressed near the base.

20. Tooth of a squalus, something like that of S. galeus, but less of a triangular form, and the lateral processes are more distinct, and also less triangular than in that species.

21. An imperfect body of a crinoid animal, encrinite of authors; the fragment is about one-half of the inferior portion of the body, from which the following description is made out, taking into view the whole circumference. The plates composing the first costal series (Miller), five in number, are longitudinally pentangular, much curved inwards towards the base, to join the first columnar joint, or perhaps the pelvis; at which part the plate is narrow, being about one-ninth of an inch, whilst the other sides are nearly three-tenths of an inch each, the superior ones being somewhat longer than the others; the second costal plates, (Miller,) five in number, are transversely pentangular, the superior joint being long, the lateral ones shortest, the former being one-half an inch in length, the latter ³⁄₂₀, and the inferior sides which articulate to the segments of the pelvis, somewhat less than ³⁄₁₀ of an inch; the margins of the first costal joints, as well as the superior margins of the segments of the pelvis, are armed with a few tubercles, some of which seem to have been perforated; all the superior pieces are wanting in our specimen, but the truncated surface, on which the scapulars (Miller) rested, is of a pentagonal outline, and composed of a series of horizontal equilateral triangles, two to each side, which are separated on each side from the adjacent pairs by a deep groove, which corresponds, and is nearly at right angles with the exterior sutures, which join the first costal joints to each other; these triangular surfaces are also separated from the exterior edge by two grooves, which are crenated, and enclose an oblong foramina between them; a single intercostal plate occurs, interposed between two of the second costals; it is of an oblong hexagonal form, its base resting upon the extremity of a segment of the first costals, which is truncated to receive it; the superior portion of this plate is much bent inward towards the abdominal cavity; its tip is quadrate and concave.

The whole exterior surface of this reliquium, with the exception of the tubercles, and sutural impressed lines, is plain and equable.

If we have not mistaken the pieces of this imperfect specimen, the pelvis is wanting, but the cavity in which it existed must have been about ³⁄₂₀ of an inch in diameter.

The plate-like form of the ossiculæ, and their mode of articulation with each other, by an extension horizontally inwards, as we have described above, in the case of those plates which we have considered as the second costals, seem to indicate, that this species ought to be referred to the second division of the crinoidea, or semiarticulata of Miller. It certainly, however, cannot be at all referred to poteriocrinites, the only genus which that author has framed in this division of the family. We refrain from distinguishing it by a name either generic or specific, until other specimens can be obtained, in which the characters are less equivocal.

We have two second costal plates, which made part of distinct individuals, larger than the above described one. Of these the surface of one is perfectly glabrous, whilst that of the other has light orbicular indentations instead of tubercles; a third very small one is perfectly smooth like the first, and doubtless formed part of the body of a young individual.

Another plate found near the same spot with the above, is of a somewhat triangular form exteriorly, or rather like the face of a truncated pyramid, of which the middle of the summit is a little produced in the form of a right angle, thus offering a scollop on each side of the apex for the adaptation of superior ossiculæ. On divesting it carefully of its extraneous matrix, we discovered that it was readily adjusted by its base to the summit of those segments of the fragment above described, which we have supposed to be second costals, a prominent line on its base corresponding with the inner one of those grooves which we have described, to characterize the superior face of those plates. This plate, then, agreeably to the relations in which we have viewed the preceding pieces, must be a scapula; it is susceptible of considerable hinge-like motion, and appears to have been much less firmly attached to the costals than the latter are to each other.

A segment of a crinoid animal, which seemed to have been a first costal joint of a pentacrinus of Parkinson, occurred near the same place.

22. Productus pectinoides, Say.—Convex valve, with a central longitudinal indentation; the whole surface is longitudinally ribbed, each rib being marked by two striæ, in addition to the central carina.

The shell is not of frequent occurrence, and a perfect specimen has not yet been obtained, but the portions we have examined, are sufficient to show that it is perfectly distinct from either of the species we have mentioned. We do not find any species figured or described by authors like it.

23. Productus compressus, Say.—Shell much compressed, with numerous acute striæ, upwards of fifty in number on each valve, the alternate ones rather smaller; a very slight central longitudinal indentation on the convex valve; outline suborbicular; hinge edge rectilinear, shorter than the greatest breadth of the shell.

Greatest breadth from ³⁄₅ to 1 inch. In its proportions it resembles the truncated portion of the productus of Martin, as represented on his plate 22. fig. 3. It is very common.

24. A shell of the length and breadth of three inches sometimes occurs, the convex valve of which is transversely undulated, its umbo prominent, and curved like that of a gryphæa, its tip resting on the base of the opposite valve which is concave, with a transverse linear base; its muscular impressions seem to have been lateral.

25. A single specimen was found of a valve of a shell, in some degree resembling a pecten, but without the auricles. Length more than 2³⁄₁₀ inches.

26. Productus lineolatus, Say.—Valves with numerous, fine, equal, equidistant, longitudinal striæ, and a few small tubercles; convex valve very much elongated, its basal portion is curved downwards, almost perpendicularly with respect to the disk near the umbones.

So singular is the structure of this shell, that the internal cavity appears to have been perfectly transverse, with respect to the general length of the shell, and small in comparison with the length. It strongly resembles the anomites productus of Martin, as represented on plate 22. fig. 102. of his Petrif. Derbi., and like that shell it is armed with small tubercles, though fewer in number, and the striæ are much more numerous and smaller.

27. Cast of a turretted univalve, probably a cerithium, of the length of 2½ inches.

28. Cast of the anterior portion of a valve of a shell like an ostrea, of the breadth of 2½ inches.

29. On the Missouri near the Platte, occur masses of rock, which seem to be almost exclusively composed of a remarkable petrifaction, belonging to the family of concamerated shells. This shell is elongated, fusiform, and when broken transversely, it exhibits the appearance of numerous cells disposed spirally as in the nummulite, but its longitudinal section displays only deep grooves. The shell was therefore composed of tubes or syphons, placed parallel to each other, and revolving laterally, as in the genus melonis of Lamarck, with which its characters undoubtedly correspond. But as in the transverse fracture, its spiral system of tubes cannot be traced to the centre in any of the numerous specimens we have examined, it would seem to have a solid axis, and consequently belongs to that division of the genus that Montfort regards as distinct, under the name of miliolites, which seems to be similar to the fasciolites of Parkinson, and altogether different from the miliolites of Lamarck. Our specimens are conspicuously striated on the exterior, which distinction, together with their elongated fusiform shape, sufficiently distinguish them as a species from the sabulosus which Montfort describes as the type of his genus. No aperture is discoverable in this shell, but the termination of the exterior volution very much resembles an aperture as long as the shell.

The length is three-tenths of an inch; and its greatest breadth one-twelfth.

We call it miliolites secalicus, Say.—Mr. T. Nuttall informs me, that he observed it in great quantities high up the Missouri.

In the same mass were some segments of the encrinus, and a terebratula with five or six obtuse longitudinal waves.

30. Another petrifaction, abundant in some fragments of compact carbonate of lime, also found on the shores of the Missouri, possesses all the generic characters which we have attributed to the preceding species, excepting that in the transverse fracture the cells distinctly revolve from the centre itself, and of course the shell was destitute of the solid nucleus as in melonis, Lamarck. It has about four volutions. We have named this species, which is, notwithstanding the difference of the central portion of the same genus with the preceding miliolites centralis, Say. As in the preceding, it is entirely filled solidly with carbonate of lime, and this substance being of a greater purity in the filled-up cavities of the fossil than in the mass, its interior divisions are very obvious.

The latter species we observed about one hundred miles up the Konzas river, where it forms the chief body of the rocks in extensive ranges. It seems to be a carbonate of lime containing iron.—James.