1874.] 251 [Rathbun. 



lower part of the umbonal region. Beaks large, acute, very promi- 

 nent anil much elevated above the level of the hinge. Their inclina- 

 tion forward is strong, as is also their inward curvature ; but they do 

 not apjiroach one another very closely in the internal moulds. Along 

 the antero-posterior axis the valves cui've rapidly upward from the 

 posterior margin, and descend quite abruptly to the anterior. The 

 internal moulds of the valves have frequently a very oblique appear- 

 ance, caused by the more convex portions tending to form a large 

 and prominent, but wholly undefined, ridge, which extends downward 

 and slightly backward from the beaks, and broadens and dies out to- 

 ward the margin. 



As only internal moulds have been obtained, the exterior markings 

 and other exterior details ^ are yet unknown. The inner margin is 

 marked with about sixteen large and prominent, rounded or flattened 

 crenulations, separated by similar interspaces ; but the plications of 

 the shell are seldom apparent on the interior. The hinge teeth are 

 not fully exposed on any of the specimens. The nnterior and poste- 

 rior adductor muscular impressions are sometimes rather deeply ex- 

 cavated ; they are generally situated nearly on the antero-posterior 

 axis, but the posterior one is at times placed slightly lower than the 

 anterior. Their longer axis is nearly vertical or inclines slightly for- 

 ward. The imprint of the anterior pedal muscle is very small and 

 entirely separated from the adductor. The size of a large specimen 

 is: length, 42 mm.; height, 39 mm.; depth of the two valves, 31 mm. 



This is a rather large form of Cardita, and is represented by sev- 

 eral internal moulds both from the cretaceous bed at Sao Jose and 

 that at Maria Fariuha, Prov. of Pernambuco, Brazil. I take pleasure 

 in dedicating this large and fine form to Col. Edwin B. Morgan of 

 Aurora, N. Y., who has so kindly and liberally aided in Brazilian 

 Exploration. 



Cardita Wilmotii sp. nov. 



Shell of medium size, moderately gibbous, length and height nearly 

 equal, depth of the two valves about one-half to two-thirds the 

 height. In outline it is subcircular ; the anterior, posterior and ven- 

 tral margins together form quite a regular curve, which is, however, 

 slightly more abrupt near where the posterior and ventral margins 

 meet ; this curve, if prolonged above to the beaks, would make 

 nearly a perfect circle. The hinge is short and equal to about one- 

 half the length of the shell. Beaks situated at a little more than 



