CYRENA. 



19 



Fig. 13. 



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

 rior iiglit violet ; epidermis light olive-gr!en ; 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; &quot; 18; &quot; 10 mill. 



Hab. South America ? (Cabinet of Prime.) 



C. regalis. 



A rare and pleasing species, the striae are deep and very regu 

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

 transversely shorter than C. solida, the posterior margin is more 

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

 regular and the &quot;epidermis is of a lighter color. 



Fig. 14. 



12. Cyrena meridional is, PRIME. Shell small, subquadrangu- 

 lar, compressed, subequilateral ; anterior side 

 semi-circular, 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; sinus narrow, curved 

 at extremity. 



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

 &quot; 35 ; &quot; 33 ; &quot; 23 mill. 



Hab. 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. 



C. 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, 



