84 CLASS I. TROPIOPODA. ORDER I. BIMUSCULOSA. 



CAPSA, Lamarck. 



Testa transversa, eequivalvis, subineequilateralis, clausa ; dentibus in 

 valva altera cardinalibus duobus, in altera cardinali unico, cum la- 

 teralibus duobus fere obsoletis. Ligamentum externum. Impres- 

 sio muscularis pallii sinu magno, oblongo. 



This genus may be said to have been instituted by Lamarck ; Bru- 

 guiere had certainly a prior claim to the name of Capsa, but it was 

 appropriated to another division of Tropiopoda, of which the Psammobia 

 rugosa formed the type. Even Lamarck, in the first instance, acknow- 

 ledged the genus Capsa as constituted by Bruguiere ; but on the forma- 

 tion of his genus Sanyuinolaria, he retained the title in reference only to 

 the species under consideration, and in this form it has been so univer- 

 sally sanctioned, that we cannot hesitate to adopt it. 



The shell of Capsa, which is closely allied to that of Donax, may be 

 described as transverse, equivalve, rather inequilateral, with the valves 

 closed and never crenulated round the inner margin. The hinge con- 

 sists of two cardinal teeth in one valve, and one cardinal with two nearly 

 obsolete lateral teeth in the other. The ligament is external, and the 

 muscular impression of the mantle exhibits a large oblong sinus. 



Examples. 



PL LXI. Fig. 1. 



Capsa Brasiliensis, Lamarck, Anim. sans vert., new edit., vol. vi. 



p. 255. De Blainville, Manuel de Malacologie, pi. 71 . f. 10. 

 Donax Bi-asiliensis , Deshayes. 



PL LXI. Fig. 2. 



Capsa complanata, Sowerby, Genera of Shells, No. 10. 

 Donax complanata, Montague. Deshayes. 



