246 AMERICAN JOURNAL 



NOTES ON RECENT AND FOSSIL SHELLS, WITH DESCRIP- 

 TIONS OF NEW GENERA. 



BY T. A. CONRAD. 



1. Description of a new genus of Venerid^e. 

 APHRODINA. Conrad. PI. 18, f. 5. 



Generic character. — Shell rounded or suboval, striated or 

 sulcated.; hinge in the left valve with three diverging cardinal 

 teeth, the anterior tooth as thick as the middle one or thicker, 

 and a straight, compressed, transversely rugose lateral tooth 

 parallel with the margin of the shell above it ; pallial sinus deep, 

 and similar to that in Caryatis, Roemer. 



The type of this genus is Meretrix Tippana, Conrad, of which 

 we have one valve only, the left, which shows the hinge, and that 

 is nearly as perfect as if the valve were a recent specimen. 



2. Note on the genus Pseudocardia, Conrad, with a descrip- 

 tion of the genus Vetocardia. 



This Cretaceous genus was indicated in a former number of 

 this Journal, but as Mr. Gabb had previously named a genus 

 Pseudocardium, it may be deemed necessary to change the 

 name. If so, it may be named 



VETOCARDIA Conrad. 



Shell subquadrate, profoundly costate ; ribs granulated or 

 fimbriated ; hinge plate thick ; right valve with one thick, pyr- 

 amidal tooth, with a pit on each side ; lunule impressed ; pallial 

 line unknown. 



The tooth is directed obliquely backwards, and, from the hinge 

 character, the genus is evidently nearly related to Astarte, though 

 D'Orbigny refers it to Venerieardia. It more nearly resembles 

 Oardita in sculpture and form, and constitutes one of those lost 

 links that have dropped from amongst living genera. Its place 

 in the system is probably between Astarte and Cardita. It 



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