o 



INOCERAMUS. 279 



Nou 1855. Inoceeamus co'sveuvs, J. Hall and F.B. Meek. Foss. Cret. Nebraska (Mem. 



Amer. Acad. Arts and Sci., 

 vol. v), p. 386, pi. ii, fig 2. 



Descrqdioii. — Valves nearly equal, considerably inequilateral, tumid, compressed 

 near the postero-dorsal margin ; lieiglit greater than length. Antero-dorsal margin 

 nearly straight ; ventral margin usually very convex ; posterior margin slightly 

 or moderately convex, forming an obtuse angle Avitli the hinge-line. Anterior 

 marginal parts more or less nearly perpendicular to the plane of the valves, some- 

 times concave near the umbo. Umbones terminal, curved inwards and forwards. 

 Ano'le between the hinge-line and the anterior margin is about 115°. The height 

 of the shell is nearly twice the length of the hinge. 



Ornamentation consists of faintly marked concentric undulations and numerous 

 sTOwtli-lines. 



Afiiiities. — In this species tlie antero-dorsal margin is relatively longer and 

 more nearly straight, and the postero-dorsal part of the shell less compressed than 

 in I. tenuis, Mantell. 



1. convexns var. qiKuJratus, Etheridge, was founded on a specimen in which the 

 anterior part of the shell is pressed in, giving rise to the appearance of a carina 

 at the upper margin of the antero-dorsal slope. 



Tvpes. — From the Totternhoe Stone of Burwell, in the Sedgwick Museum, 

 Cambridge. 



Disirih'ution.- — Upper Greensand (zone of I'ecten a^per) of Warminster. 

 Cenomanian of Wilmington, Devon. Chalk Marl of Branscombe, Beer Head, 

 Titherleigh (near Chard) and Hunstanton. Totternhoe Stone (zone of Holastcr 

 siih(j]iihosiis) of Burwell. 



Inocebajius ric'iTS, Sou-erhy, 1829. Plate XLIX, figs. 5, G. Text-fig. 36. 



1829. Inoceeamus picius, J. cle C. Soverly. Min. Couch., vol. vi, p. 215, pi. dciv, 



fig. 1. 

 1854. -- picTus, J. Morris. Cat. Brit. Foss., ed. 2, p. 170. 



1867. — ANGULATUS, E. Gveroiiger. Album Paleout. de la Sarthe, p. 



20, pi. XXV, fig. 7 (? I. ANGULATirS, 



cVOrhigmj, 1846). 

 1904. — picivs,E.T.Neiitona,nCiA.J.Ji(l-es-Bro2ime. In Jukes-Browue, 



Cret. Rocks of Britaiu, vol. 

 iii, p. 450. 



Dvficrijitlov. — Shell equivalve, very inequilateral, slightly or moderately convex 

 with flattened sides ; the postero-dorsal part compressed. Antero-dorsal marginal 



