ICO CRETACEOUS LAJilELLlliKANCHIA. 



0'c'M(«— MUTIELLA, Slulic::lca, 1871. 

 ('Palaeout. ludica, Cret. Fauua S. India,' p. 247.) 



MuTiELLA ? CANALICULATA (Sowerbi/), 183G. Plate XXV, figs. 4 — G. 



1836. Peteicola canaliculata, /. de C. Sowerby. Trans. Geol. Soc, sor. 2. vol. 



iv, pp. 241, 341, pi. xvi, 

 fig. 11. 



— — NUCiFOEMis, Sowcrhij. liiitl, pp. 241, 341, pi. xvi, lig. lU. 

 1850. Cakdium canaliculatum, A. d'Orhiijnij. Prodr. de Pal., vol. ii, j). 1(J3. 



— — NUCIFOKME, d'Orhijni/. Ibid., p. 163. 



1854. Petkicola ? canaliculata, /. Morris. Cat. Brit. Fuss., ed. 2, p. 220. 



— — NUCIFOEMIS, Morris. Ibid., p. 220. 



1866. Caedium canaliculatum, F. J. Pictet and G. Campic/ii;. Foss. Terr. Crct. 



Ste. Croix (Mater. Pal. 

 Suisse, ser. 4), p. 270. 

 1865-6G. Petkicola nucifoumi.s, Pictet and Campiche. Ibid., pp. 163, 276. 

 1870. — canaliculata (Caedium), F. UtoIiczJca. Palajout. ludica, 



Cret. Fauna S. India, vol. 

 iii, p. 141. 



— — NuciFoKMis {'f CoKBis), StolicxJia. Ibid., p. 141. 



Description. — Shell iiiHated, outline mure or less orbicular, hie(juilateral, length 

 and height eciual. Margins rounded, xlnterior margin less convex than the pos- 

 terior margin. The latter makes an obtuse angle with postero-dorsal margin and 

 curves rapidly to join the ventral margin. The margin in front of the umbo 

 expands. Umboues large, contiguous, curving inward and forward. No lunule. 



Ornamentation consists of numerous, regular, radial ribs, separated by narrow 

 furrows, and crossed l)y narrow concentric ridges which ai'c more prominent 

 on the posterior part of the shell than elsewhere. Inner margins of the valves 

 crenulate. 



There are two cardinal teeth in the left valve and one in the right. Behind 

 the umbo a long, nearly straight, sharp ridge forms the inner margin of the 

 ligament groove. 



Measurements .- 



(1) (-') (a) 



Length . 20-5 . I'J . 17 



Height . 20-5 . 19 . 17 . 



^1—4) Blackdowu. 

 Affinities. — The generic position ol' this species has been for a long time a 

 matter of doul)t, l)ut no one appears to have accepted Sowerl)y's view. The 



