408 CEETACEOUS PELECYPODA 



5. Ikoceeamus labiatus, ScUothevm, PL XXIX, Fig. 1. 



1813. Ostracites lahiatus, Schlotlieini, Bronn's Jahrb., vol. vii, p. 93. 



1820. Mytulites prohlematicus, Schloth., Petrsefactenk., i, p. 302. 



1822. Mytiloides lahiatus, Brogn., Cuv., Oss. foss., pi. 3, %. 4 in Geol. des env. de Paris. 



1822. Inoceramus mytiloides, Mant., Geol. of Sussex, p. 215, pi. 27, fig. 2, pi. 28, fig. 2. 



1823. „ » Sowerby, Min. Concli., V, p. 62, pi. 442. 

 1827. Catillus Schlotheimii, Nils son, Petraef. Suec, p. 19. 



1836. Inoceramus mytiloides, Goldf., Petraef., Germ., II, 188, pi. 113, fig. 4. 

 X843. „ prohlematicus, d'Orbigny, Pal. fran^. terr. cret.. Ill, p. 510, pi. 406. 



/. lahiatus, prohlematicus aut mytiloides, auctorum. 



I, testa suh-ovata^ pUts mmusve complanata, multo longiore quam alta, umbonibus 

 anticis, paulo prominentibus, depresse incurvis ; margine cardinali brev% fere recto, 

 oblique descendente, margine antico et post-dorsali levissime curvatis, marg, postico 

 sub-rotundato ; superficie rugis et plicis concentricis ornata. 



Specimens from South India are in every way identical with those from 

 Europe ; the variations as to greater or lesser flatness of the valves being the 

 same. The valves of small specimens often appear to be a little more convex 

 than those of large shells, which in India sometimes attain a size of about 

 200 m. m. in length and about 120 m. m. in height. 



Localities, — North-east of Kauray, Odium, Puravoy, Moraviatoor, Ootatoor, 

 Monglepaudy, &c., mostly in a yellowish, highly calcareous and earthy sandstone. 



Formation, — Ootatoor group. 



In Europe the species has been noticed from the Turon and Cenoman beds 

 of Erance, from the lowest beds of the upper series of the German Plgener, from 

 the lower Chalk of England, &c., &c. Roemer found it in Texas, and it has since 

 been observed in various parts of the United States of North America. 



It is a noticeable and interesting fact that the general geological position of 

 I, labiatus in India closely corresponds with that noticed in Europe, where it generally 

 occurs in beds lower than those containing I. Cripsianus, The latter exclusively 

 characterizes in India the uppermost series of the cretaceous deposits, the former 

 is equally characteristic for the lowest series, — Ootatoor group, — occurring with 

 Am. Rotomagensis, rostratus, (=^ inflatusj, and other well known European fossils. 



6. Inoceramus simplex, Stoliczka, PI. XXVIII, Eigs. 3-4. 

 I, testa sub-ovata, mytiloidea, modice complanata, postice paulo dilatata, umboni- 

 bus approximatis, obtusis, margine cardinali postice extenso, oblique descendente 

 marg, post-dorsali vix curvato, rectiusculo, ventrali leviter insinuato, postico 

 sub-rotimdato ; superficie plicis concentricis irregularibus^ parum distinctis et striis 

 distantibus lamelliformibus notata, 



A regular mytiloid form with depressly convex, posteriorly somewhat pro- 

 duced and compressed valves ; the ventral side is slightly indented, the posterior 

 very little convex ; the hinge-line is straight, posteriorly obliquely produced, 

 provided internally with numerous small ligamental pits. The surface exhibits 

 some indistinct plications and distant lines which mark the extent of the different 

 successive layers of growth. 



