10 AMERICAN CORBICULAD.iJ. 



The genus Batissa was established in 1S52, by Mr. Gray, for a 

 class of shells heretofore included under the genus Cyrena, and 

 represented by the Cyrena violavea. The principal differences 

 between the Cyrena proper and the Batissa are the following : the 

 Bafissa have compressed serrulated lateral teeth, the ligament is 

 very large, rounded and prominent, the epidermis is dark and the 

 palleal impression always simi)le. The hinge of the Batissa offers 

 some analogy to that of the Cor'bicula, but is different in* so far, 

 that the anterior lateral tooth in Batissa is always short and much 

 smaller than the posterior tooth. 



The animal, according to Mr. Gray,* is similar to that of Cyrena. 



The species of Batissa, very limited in number, are confined in 

 their geographical distribution to the countries and islands of the 

 Indian Ocean. I am not aware that as yet any have been found 

 in a fossil state. 



This new genus does not seem to have been received with much 

 favor by conchologists, and more especially by those of the conti- 

 nent. Mr. Deshayes adopted it in 1854,'' in describing some new 

 shells from the Cuming Collection, but since then^ he has changed 

 his views on the subject. I was the first to bring it into notice in 

 this country.* 



(This genus is not represented on this continent.) 



VELORITA, Gray.s 

 Cyrena, Gray, 1825. — Venuf;, Gray, 1828. — Velorita, Gray, 1834. 



Animal not observed. 



Shell trigonal, higher than broad, heart-shaped, thick, inflated, 

 posteriorly angular ; hinge broad, thick, three unequal cardinal 

 teeth, compressed, a little oblique, anterior tooth in the right 

 valve very short, posterior tooth in the left valve obsolete ; lateral 

 teeth very unequal, anterior tooth thick, short, transverse, very 

 close to the hinge, posterior tooth elongate, lightly striated, re- 

 mote from the hinge ; muscular impressions rounded, equal ; pal- 



' Bivalves of the Brit. Mus. 18.')4, 234, 



2 Proc. Zool. XXII, 1854, 13. 



^ An. sans vert, basin de Paris, I, 1860, 484. 



* Ann. N. Y. Lyceum, Nat. Hist. VII, 1860, 112. 



5 Griffith's Cuvier, 1834, pi. 31, f. v. 



