to flat; cavity shallow and remarkably contracted towards the hinge, which is elongated, having a deep and broad cavity in the lower valve, with a corresponding rounded and striated ridge in the opposite valve. This large oyster measures nearly two feet from beak to base. The contracted form of the cavity is most striking in the oldest individuals. Probably a Miocene shell. Locality.-Oyster Point, Mexico. ANOMIA, Lin. ANOMIA SUBCOSTATA. PLATE XIX, FIG. 1 a, b. Anomia subcostata, Con. Proc. Acad. Nat. Sc., vol. VII, p. 267. Obtusely ovate, rather thick; umbo of larger valve ventricose; hinge thickened, surface of the valve obtusely undulated concentrically, and marked with waved, wrinkled, interrupted ribs, much raised, except towards the base, where they are larger and somewhat tuberculiform; upper valve entire, or with obsolete radii towards the base. This has a general resemblance to A. Ruffini, Con., of the Virginia Miocene, but is much thicker and very distinct. CARDITA, Lam. Blain. CARDITA PLANICOSTA. PLATE XIX, FIGURE 2, a, b. Venericardia planicosta, Lam. An. sans Vert., vol. V, p. 669. Desh. Coq. Foss., vol. I, p. 149. Cardita planicosta, Blainville. Ovate-oblique, cordate, very thick, with flattened broad ribs, 22-24, granulated towards the apex; lunule very profound, wide, cordate, margin crenate within, cardinal teeth two, finely striated. This species is found in Virginia and Alabama, as well as in California. Deshayes describes the Paris specimens of C. planicosta as crenulated on the ribs near the summit, a character scarcely visible in the specimens that I have examined. Locality.-Arroyo las Minas, between Eagle Pass and Leon. CORBULA, Lam. CORBULA NASUTA. PLATE XIX, FIGURE 4. Corbula nasuta, Con. Foss. Shells of Tert. Form. Corbula Alabamiensis, Lea, Cont. p. 45, pl. I, fig. 12. Inflated, triangular-ovate, very inequivalve, ventricose; finely striated concentrically; buccal end rounded, longer than the anal, which is contracted; flexuous, narrow, and obliquely truncated at the end. Locality.-Western Texas. VENUS VESPERTINA. PLATE XIX, FIGURE 5, a, b. Subtriangular, inequilateral, convex; length and height equal; buccal end acutely rounded; anal end more obtuse; summit prominent. A small Eocene species, with the external surface somewhat worn. concentric lines. Locality.-Western Texas. It appears to have had CYTHEREA, Lam. CYTHEREA NUTTALI. PLATE IV, FIgure 5. Cytherea Nuttali, Con. Foss. Shells of Tert. Form. Subrotund, inflated, equilateral, ornamented with fine, regular, concentric lines, anal end obtusely rounded. An Eocene species, found both in Texas and Alabama. Locality.-East of Frontera, associated with Cassidula alveata. VOLUTALITHES, Swainson. VOLUTALITHES SAYANA. PLATE XIX, FIGURE 6. Voluta Sayana, Con. Foss. Shells of Tert. Form. Voluta parva, Lea, Cont., p. 173, pl. VI, fig. 181. Turbinate, with revolving impressed lines; coronated; shell thin; volutions 7, subangulated; body volution either smooth or with longitudinal acute lines or folds. There is only one small specimen of this abundant Claiborne species. It is imbedded in the same piece of rock which contains Corbula nasuta and Natica limula. Locality.-Western Texas. NATICA, Lam. NATICA LIMULA. PLATE XIX, FIGURE 7. Natica limula, Con. Foss. Shells of Tert. Form. Natica mamma, Lea, Cont. to Geol., p. 109, pl. IV, fig. 95. Subglobose, flattened at base; spire rounded, pointed at the apex; columella much thickened above; umbilicus large; shell thin; mouth ovate. Locality.-Same as preceding. TURRITELLA, Lam. TURRITELLA PLATE XIX, FIGURE 8. This figure represents a specimen of tertiary rock from San Diego, California. Besides the Turritella, which is not determined, there are a few small unknown bivalves. CASSIDULA, Humphreys. Sub-genus LACINIA, Con. CASSIDULA ALVEATA. PLATE XIX, FIGURE 9. Melongena alveata, Con., Amer. Jour. Sci., vol. XXIII, p. 344. Sub-globose, with revolving robust lines, and a wide, concave, revolving furrow below the angle of the large volution; spire very short; suture deeply impressed, sub-canaliculate. Locality.-Western Texas. APPENDIX. CRETACEOUS FOSSILS. CARDITA SUBTETRICA. PLATE XXI, FIGURE 5. Sub-orbicular, slightly ventricose; ribs 22? not very prominent, rounded, squamose, ribs and interstices about equal in width. This may be an eocene species; I do not know any of its associated fossils. PHOLADOMYA SANCTI-SABÆ. PLATE XXI, FIGURE 4. Cardium Sancti-Saba, Romer, Kreide. von Texas, p. 48, pl. VI, fig. 7. Inequilateral, longitudinally ovate, gibbous, posteriorly compressed, produced, sub-caudate, smooth; the rest of the shell radiate-costate; ribs 16, equal, granulated, becoming obsolete posteriorly; umbo large, prominent, anterior to the middle. Localities.-Leon Springs; New Braunfels, Texas. CAPSA, Lam. CAPSA TEXANA. PLATE XXI, Figure 6. Oblong-oval, disk flattened or depressed in the middle; radii distinct, close, rugose posteriorly, gradually becoming obsolete in the middle of the valve; buccal end regularly rounded ; anal end truncated, direct. Locality.-Leon Springs. TEREBRATULA LEONENSIS. PLATE XXI, FIGURE 2. Inequivalved, oval or sub-petagonal; rostral end ventricose, rounded in the middle, and the sides obliquely convex-depressed; umbo small; foramen small, almost touching the umbo; imperforate valve less convex; valve widest above the middle, rapidly tapering to the front, which is slightly depressed; front margin narrow and truncated; surface elegantly and minutely punctate. Narrower in front than T. Wacoensis, Romer. I cannot compare it with Shumard's figure of T. Choctawensis, as that figure, in the Palæontology of Red river, like all the representations of fossils in that work, (except Gryphœa Pitcheri,) is worthless for the purpose of identification. The punctuated surface is so common in the genus that it has no value in specific distinctions. Locality.-Leon Springs. TURRITELLA LEONENSIS. PLATE XXI, FIGURE 7, a, b. Volutions sub-angular, each with three distant, large, crenulated, revolving ribs, and an intermediate crenulated line; spire rapidly tapering to the apex; body volution large, rounded at base, which has four or five fine revolving ribs. A limestone cast; traces of shell show oblique longitudinal folds or ribs. HAMITES LARVATUS. PLATE XXI, FIGURE 8. Hamites larvatus, Con. Proc. Acad. Nat. Sci., vol. VII, p. 265. Ovate-oval, obliquely ribbed; beak and front obtusely rounded or sub-truncated; ribs oblique, distant, very prominent, acute, unequal, frequently alternated, obsolete on the back, and having a tubercle on the front margin or angle; ribs on the front thickened and obtuse; sides of the shell flattened, and the rib margin nearly rectilinear; smaller ribs generally without a distinct tubercle. I have amended the former description of this species from the specimen here figured. In the Arkansas specimen the ribs are alternated, the smaller one being without a tubercle; but the former has three equal ribs with the tubercle on each, and above them is the smaller rib without it. Traces of the shell show annular striæ. Localities.-Leon Springs, Texas; White river, Arkansas. |