CYRENA. 



19 



Fig. 13. 



approximate at apex, eroded; strise deep, very regular; valves solid, inte- 

 rior light violet ; epidermis liglit olive-green ; hinge- 

 margin slightly curved, broad ; cardinal teeth 

 strong, unequal, divergent, the posterior ones bifid ; 

 lateral teeth unequal, depressed, posterior distant ; 

 sinus irregular in shape, long and tapering at ex- 

 tremity. 



Long. 0.76 ; Lat. 0.73 ; Diam. 0.43 inches. 

 " 19; " 18; " 10 mill. 



Hab. South America ? (Cabinet of Prime.) 



.'jnli.s. 



A rare and pleasing species, tlie strice are deep and very regu- 

 lar, which distinguish it from others ; it is smaller, less inflated and 

 transversely shorter than 0. soluki, the posterior margin is more 

 produced at the extremity, the sinus is longer, the striae are more 

 regular and the epidermis is of a lighter color. 



Fig. 14. 



12. Cyrena meridionalis, PEniE. — Shell small, subquadrangu- 



lar, compressed, subequilateral ; anterior side 

 semi-oircula% a little produced; posterior side 

 subabrupt ; beaks small, inclined anteriorly, ap- 

 proximate at apex, eroded ; striae delicate, rather 

 irregular; epidermis light brownish-green; 

 valves solid, interior light violet ; hinge-margin 

 slightly curved ; cardinal teeth strong, unequal, 

 divergent, central tooth bifid ; lateral teeth com- 

 pressed, small, subequal; siuus narrow, curved 

 at extremity. 



Long. 1.40; Lat. 1.32; Diam. 0.92 inches. 

 " 35; " 33; " 23 mill. 



Bub. South America, at Payta, in Peru. (Cabinet of Prime.) 



The external appearance of this species brings it near C. ordi- 

 naria ; it is, however, much more transverse, and the hinge-mar- 

 gin is broader and less curved. A rare species. 



0. meridionalis. 



13. Cyrena ordinaria, Prime.— Shell small, trigonal, transversely 

 very short, compressed, subequilateral ; anterior side semi-circular ; pos- 

 terior side rounded from the beaks downwards, subabrupt at extremity ; 

 beaks prominent, small, inclined anteriorly, approximate, eroded ; striae 

 fine, irregular, epidermis light brownish-green ; valves solid, interior light 

 violet ; hinge-margin curved, broad ; cardinal teeth unequal, divergent, 



