358 



Genus INOCERAMUS, Sowerby. 



INOCERAMUS CRIPSII ? var. SUBUNDATUS. 



Plate 3, figs. 1, 1 a, and 3, 3 a. 



Inoceramus Ci-iiisii, Mautell (1822), Fossils South Downs, or lUiist. Geol. Susses, 133, pi. 

 xxvii, fig. 11.—? Goldf., Petref. Germ., ii, 116, figs. 4, «, &.— Zittel (1864), Bivalves 

 of the Gosau Formation, tab. xiv, figs. 1 and 2 (varieties and synon. ?). 



? Inoceranus Barahtni (part), Morton (1834), Synopsis Org. Rem., 62, pi. 13, fig. 11. 



Inoceramus subuiHlatus, Meek (1861), Proc. Acad. Nat. Sci. Philad., xiii, 315. * 



Shell (riglit valve) snbovate or triincato-siibcircular, 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 binge. Surface ornamented by regular concentric 

 undulations, separated by concave spaces of nearly uniform size, and 

 ob.scure 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. Cripsii of Mautell, 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 speci- 

 men, and only know it from his imperfect figure and very brief descrip- 

 tion, 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, /. Barahini, that is also generally con- 

 sidered a synonym of I. Cripsii. Morton, however, included two forms 

 that may or may not be varieties of one species. One of these is repre- 

 sented by figures 2 and 2 a of our plate 3, drawn from Morton's original 



Inoceramus Barahini, 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 com- 

 parison, but its identity with that species seems at least not very clearly 

 manifest. 



