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Show 358 Genus INOCERAMUS, Sowerby. INOCEEAMUS CRIPSII ? VM. SUBUNDATUS. Plate 3, figs. 1,1 a, and 3,3 a. inoceramms Cripsii, Mantell ( 1822), Fossils South Downs, or Illust. Geol. Sussex, 133, pi. xxvii, fig. 11.- f Goldf.,. Petref. Germ., ii, 116, figs. 4, a, b.- Zittel ( 1864), Bivalve* of the Gosau Formation, tab. xiv, figs. 1 and 2 ( varieties and synon. f). ? Inoceranu* Barabini ( part), Morton ( 1834), Synopsis Org. Rem., 62, pi. 13, fig. 11. Inoceramus subundatus, Meek ( 1861), Proc. Acad. Nat. Sci. Philad., xiii, 315. Shell ( right valve) subovate or truncato- subcircular, rather gibbous; anterior and posterior margins rounding more or less regularly into the base, so as to form with the latter about three- fourths of a circle; hinge equaling a little more than two- thirds of the entire length of the shell; beak small, rather obtuse near the anterior margin, and rising but slightly above the hinge. Surface ornamented by regular concentric undulations, separated by concave spaces of nearly uniform size, and obscure concentric striae. Length, 2.23 inches; height, 1.95 inches; convexity of right valve, 0.70 inch. I have long been greatly at a loss what disposition to make of shells of this type. In Europe, various forms more or less nearly like this are generally referred to I. Cripdi of Mantell, though it has always seemed to me that several of them are distinct from Mantell's type. Yet we in this country, who have never seen Mantell's original specimen, and only know it from his imperfect figure and very brief description, are greatly at a loss in regard to its exact specific limits. The question in regard to the proper name to retain for these shells is also further complicated by the fact that Dr. Morton in this country long back described a species, /. Barabini, that is also generally considered a synonym of I. Cripsii. Morton, however, included two forms that may or may not be varieties of one spefcies. One of these is represented by figures 2 and 2 a of our plate 3, drawn from Morton's original Inoceramus Barabini, Morton. These figures were taken from Dr. Morton's type specimen. specimen, which is an imperfect cast. The other form, represented by the above cut, also made from Dr. Morton's specimen, represents the more elongated form, which is also imperfect. The latter agrees more nearly with Mantell's original so far as we have the means of comparison, but its identity with that species seems at least not very clearly manifest. |
