nearly the form of the European B. trilobatus, but with very different surface characters. Formation and locality. From the shales of the Hamilton group at Norton's Landing, Cayuga lake, N. Y. BELLEROPHON CREXISTRIA. PLATE XXV, FIGS. 16–18. Bellerophon crenistria, HALL. Illustrations of Devonian Fossils: Gasteropoda, pl. 25. 1876. SHELL Ovoid. Inner volutions small and gradually enlarging, partially exposed in the umbilicus; outer volution ventricose, somewhat rapidly and regularly expanding to near the aperture, where it is more abruptly spreading; rather broadly and abruptly sinuate in front; flattened or slightly concave on the dorsum, the flattened portion distinctly limited, and the margins often subcarinated by stronger longitudinal striæ. On each side of these limits the shell is usually more or less depressed, giving a subtrilobate aspect to the body-volution. SURFACE marked by distinct revolving stria which are regularly crenulated, producing a papillose aspect; the crenulations are arranged parallel to the lines of growth, curving forward from the umbilicus, and thence gently backward over the periphery; these lines are usually distinctly arched upon the flattened or concave dorsum. This species is so conspicuously different from every other one in the formation under consideration that there are no features for comparison. The general aspect of the outer volution is subtrilobate, with the margins somewhat spreading and the front sinuate. The dorsal band is limited on each side by stronger single, or sometimes duplicate revolving striæ, presenting a slightly different aspect in the crenulations which are more oblique; two or three of the central striæ are sometimes apparently quite independent of the others in the arrangement of the crenulations. In different individuals the revolving striæ exhibit considerable variation; in some they are continuous with slightly nodulose elevations, and in others, distinctly pustulose-the prevailing character being that of interrupted longitudinal striæ, with the intermediate spaces reaching the even surface of the shell. Formation and localities. This species has thus far proved a rare form, though having rather a wide geographical distribution in the shales of the Hamilton group. It occurs near Summit, in Schoharie county; at Sherburne creek, in Chenango county; at Borodino, on Otisco lake; at Norton's Landing, on the east side of Cayuga lake; and at York, in Livingston county. With one exception, only a single specimen has been obtained at each of these localities. SPECIES OF THE CHEMUNG GROUP. BELLEROPHON TRILIRATUS. PLATE XXIV, FIGS. 2, 16-19. Bellerophon (Phragmostoma?) tricarinata, HALI. Illustrations of Devonian Fossils: Gasteropoda, pl. 22. 1876. Not B. tricarinatus, SHUMARD. 1858. SHELL Subhemispheric. Inner volutions comparatively small, the outer one extremely dilated, and in its normal condition very ventricose. ventricose. Aperture greatly expanded, the peristome flattened and slightly repand, with a rather strong and moderately deep sinus in the anterior margin; auriculated posteriorly and nearly enclosing the volution in that direction. SURFACE marked by distinct revolving striæ, which in the casts are indicated by sharp narrow grooves, with a flattened interspace of three or four times. the width, the direction being often slightly undulating. Finer and less conspicuous striæ mark the entire surface and become more distinct towards the margin. The dorsal line is marked by a bicarinate band, which when well-preserved, shows a narrow depression of about one-sixteenth of an inch wide at the margin, and half that width at the columella, bounded on each side by a sharply defined line. On each side of this carina and equidistant from it, is an angular fold extending from the columella, from one-third to one-half the length of the expanded portion of the volution, and gradually becoming obsolete. The expansion is sometimes marked by three or four concentric wrinkles, having a regularity which might seem to indicate specific value, but other well-marked specimens are destitute of this feature. The interior characters are unknown, except as seen in a single specimen, which shows the inner volutions small, and the carina extending into the posterior part of the aperture. The expanded outer volution has a width of one inch and three-fourths to two inches, with an antero-posterior diameter of one inch and a half to one and three-fourths. A single specimen has a width of two and a quarter inches. In its revolving striæ this species bears some resemblance to B. lyra, which has stronger striæ and an elevated dorsal band, over which the concentric striæ are strongly arched. In general form it resembles B. patulus and B. rudis, but the volutions are less rotund and the outer one is marked by a bicarinate dorsal band and laterally by diverging angular ridges. These features, together with the fine, regular revolving striæ, sufficiently characterize the species among all the known forms of the rocks of New York. Formation and locality. In the Chemung group, in the vicinity of PaintedPost, Steuben county, N. Y. BELLEROPHON TRILIRATUS, juvenis ? PLATE XXVI, FIGS. 15, 16. SHELL Subtrilobate, gibbous, becoming ventricose towards the aperture; dorsum obtusely angular or with a rounded carina; dorso-lateral ridges distinctly angular and subcarinate. Umbilicus apparently not closed; peristome sinuate anteriorly. The prominent subcarinate dorsum and strongly angular dorso-lateral margins, with concave intermediate spaces, are conspicuous features. The specimens are casts of the interior, and preserve no surface-markings. All the typical forms of B. triliratus which I have seen are casts of the interior, or extremely macerated specimens, but still preserving some evidence of revolving or radiating striae; while in these smaller shells there is no evidence whatever of such striæ. I do not, however, at present find any sufficient reason for separating them from those figured on plate 24, in which the posterior part of the last volution is distinctly tricarinate. BELLEROPHON MERA. PLATE XXV, FIGS. 9-14; AND PLATE XXVI, FIGS. 19-24. Bellerophon Mara, HALL. Illustrations of Devonian Fossils: Gasteropoda, pl. 22. 1876. 66 Not 66 66 66 Geol. Rep. U. S. Survey, 40th Parallel: CLARENCE KING, Geologist (in MS.). SHELL Subglobose, or broadly subovoid; length about equal to the greatest width at the aperture; in imperfect specimens the width is usually greater than the length. Inner volutions small and gradually enlarging to the third, which is more rapidly expanded, the exposed portion of the outer one being extremely ventricose. Aperture greatly expanded, the peristome broadly sinuate in front and auriculate at the sides; somewhat thickened and repand as it approaches the umbilicus, over which it extends, continuing in a thickened callosity across the columellar side. The dorsum is marked by a distinct carina and the entire surface by strong pustulose striæ, or rows of pustules, which are arranged along lines parallel to the striæ of growth. The dorsal carina is also pustulose. These markings are somewhat less conspicuous on the anterior and lateral margins of the shell. This fossil, when entire, presents a strong rotund form until near the aperture, where it becomes abruptly expanded. The shell is thick, and the surface completely studded with rows of pustules which, in one direction, are arranged in series parallel to the lines of growth in the shell, and, in the other direction, in diagonal lines crossing these, giving the aspect of a quincunx arrangement. On the removal of the shell the carina on the cast usually extends but a short distance from the margin of the aperture, and the dorsum beyond this is obtusely or obscurely angular. In a few examples, which present no marks of specific distinction, the carinate dorsum is continuous for the entire extent of the exposed part of the volution. The casts are quite smooth and even, with the exception of the angular or subcarinate aspect of the dorsum upon a part of the outer volution. The figures 9-14 of plate 25 are from gutta-percha impressions in molds of the exterior of the shell. A few individuals preserve a portion of the shell, sufficient to identify the surface-markings; but by far the larger number are casts of the interior, preserving some portion of the shell in a crystalline condition. The figures on plate 26 illustrate the species as it occurs in casts, and with the imperfectly preserved shell. A single example, of unusual size, has the exterior of the shell nearly removed by maceration and solution, but still preserving some of the surface-markings. The specimen, figure 19, plate 26, is one which has been subjected to maceration and a solution of the superficial portion of the shell, leaving a smooth surface, so far as the ordinary markings are concerned, but which has not quite the condition of a cast of the interior, though scarcely differing therefrom, except in the preservation of the dorsal carina. On the recurved portions of the volution some faint remains of pustules are visible, and another specimen in the same association is quite pustulose. This species occurs in the central portion of the Chemung group somewhat rarely, but in the higher beds it is abundant at one or two localities. In its surface characters it is quite distinct from any other species in the formations under consideration, but resembles in a great degree the B. tuberculatus of FERUSSAC and D'ORBIGNY.* Formation and localities. In the shaly beds of the Chemung group at Philipsburgh, Allegany county, N. Y., and in sandstone below the conglomerate near Mansfield and Tioga in Pennsylvania; at Howard in Steuben county, and abundantly at Nichols, Tioga county, N. Y. * Bellerophon tuberculatus, FERUSSAC & D'ORBIGNY. Monogr. Cephal., pl. 8, Figs. 7–10. D'ARCHIAC & DE VERNEUIL. Rhenish Provinces, p. 353, pl. 28, Fig. 9. GEINITZ. Grauwackenformation in Sachsen, Hft. ii, S. 44, Taf. 11, Fig. 12. |