IXOCERAMUS. 



301 



Nou 1882. Inockkamus cardissoides, H. Schroder. Zeitscbr. d. deutscli. geol. 



Gesellscb., vol.xxxiv, p. 271, 

 j>l. xvi, fig. 1. 



Dei^criplion. — Sliell very inefniilatcral, oblique, moderately convex, -with the 

 anterior marginal part sloping rapidly. Height considerably greater than length. 



Fta. 



Fio. .-)S. 



\ 



^r 



.y 



UC^^•'■■'- 



p5^''^. . > 





f f, 



Fia 57 -7»ocei-amus cardissoides. Goldf. Upper Chalk (proKably zone oi ActinocauKix quadratus). near 



Speeton. Sedgwick Museum. Left valve. Posterior wing missing. Isatiual size. 

 Fio 58 -/no«.-a.»iis cardissoides. Uoldf. Upper Chalk, probably Kent. British Museum. No. 98209. 



Part of left valve. Natural size. 



Ventral margin convex; anterior margin slightly curved. A broad concave 

 depression extends from behind the umbo to the postero-ventral extremity, and is 

 limited posteriorly by a straight, sharp ridge, behind Avhich is a wing-like part of 

 the shell. 



Ornamentation consists of strong, widely separated concentric ribs, with a steep 

 ventral slope and a more gentle dorsal slope; in the interspaces are small con- 

 centric ribs, which arc crossed by small radial ribs giving a more or less distinctly 



40 



