INVERTEBRATE PALEONTOLOGY. 149 



2. VENILICARDIA. Stoliczka. 



Shell generally large, thick, ami less angular in outline than the 

 last, with umbonal slopes evenly convex, or merely prominently 

 rounded, and surface concentrically striated: hinge with the posterior 



cardinal tooth of the rigid valve sometimes very strongly bifid, and at 

 its anterior end curved downward ; and the anterior -cardinal of eacli 

 valve long, flexuous, and at the posterior end tubercular. — Cyprina 

 bifida, Zittel. 



The above characters of t lie cardinal teeth of Venilicardia were evidently 

 taken by Dr. Stoliczka from Cyprina bifida of Zittel (which he seems to 

 regard as the type of the group), and not from his own V. obtruncata, the 

 only Indian species figured by him. The latter is a large, very gibbous, 

 thick, subquadrangular shell, that has the posterior cardinal teeth much 

 elongated, very oblique, entire, attenuated, and gently arcuated along their 

 whole length. The middle cardinal of its left valve is also obliquely some- 

 what elongated, instead of being trigonal, as in the typical Veniella; while in 

 the right valve it is also more oblique, and occupies a lower position than in 

 the typical Veniella. It, is likewise much larger than that of the same valve 

 in his type of Venilicardia, in which, in fact, this tooth appears to be nearly 

 obsolete, or only represented by a slight thickening of the anterior curved- 

 down point of the posterior cardinal. On comparing the hinges of these two 

 shells (V. bifida and V. obtruncata) as figured by Zittel and Stoliczka, it will 

 be seen that the latter differs quite as decidedly from V. bifida, the type ol 

 Venilicardia, as that shell does from the typical Veniella. It is evident, how- 

 ever, that the hinge-teeth of the Cretaceous shells of this kind vary consid- 

 erably in details, so that.it is better not to make farther subdivisions until 

 the extent of these variations can be determined by the examination of the 

 hinges of other species. 



Dr. Stoliczka also includes, as another subgenus under Veniella, a genus 

 d. 'scribed by Munier-Chalmas, in 1863, under the name Anisocardia, the 

 type of which is the Kimmeridge-clay (Wealden) species, A. elrga>/s, 

 M.-Chalmas. This is a circular shell, with elevated, rather pointed, nearly 

 central, somewhat obliquely incurved beaks, and small but well-defined, 

 regular radiating surface-costae, and distinctly-crenated free margins within. 

 Its hinge-margin is weaker, but (he teeth of its hinge seem to be rather 



