14 AMERICAN CORBICULAD^E. 



bears great resemblance in outline, it is very much less fell, trans 

 versely broader, and the epidermis is not so dark; it is very 

 closely allied to C. solida. Found not unfrequently. 



4. Cyrena solida, PHILIPPI. Shell rounded, somewhat oblique, 



heart-shaped, thick, solid, inequilateral, 



Fig. 8. very much inflated ; anterior side rounded, 



posterior abrupt at extremity ; beaks small, 

 acute, curved inwards, appproximate at 

 apex, entire ; striae regular, coarse ; epider 

 mis dusky greenish-brown ; interior of the 

 valves violet ; hinge-margin curved, thick, 

 cardinal teeth divergent, unequal, anterior 

 ones bifid ; lateral teeth unequal, anterior 

 conical approximate, posterior narrow, 

 elongated ; sinus broad at mouth, short, 

 C. solida. acute at extremity. 



Long. 1.2 ; Lat. 1.09 ; Diam. 0.7 inches. 

 &quot; 34; &quot; 31; &quot; 23 mill. 



Hab. Nicaragua and Balize. (Cabinets of Hanley, Smithsonian Insti 

 tution and Prime.) 



Cyrena solida, PHIL. Abbild. II, 1846, 78, pi. xv, f. 9. 



This species is very closely allied to the C. radiata, with which 

 it is often confounded, it is, however, smaller, more inflated, the 

 striae are not so regular, the epidermis is usually darker and with 

 out polish ; some specimens exhibit on the epidermis the perpendi 

 cular rays common to C. radiata and Corb. limosa. 



5. Cyrena triangula, v. d. Buscu. Shell solid, obliquely subtri- 

 angular, subequilateral, somewhat ventricose ; posterior dorsal slope an 

 gular, anterior less so, ventral margin arcuate; beaks nearly central, ele 

 vated ; pointed, incurved, generally perfect ; exterior calcareous, compara 

 tively smooth, covered with a light ashy-green epidermis ; interior of the 

 valves variable, sometimes entirely violet, at others white with violet on 

 the margins or flesh color on the muscular impressions ; hinge-margin 

 thick, three unequal and rather small cardinal teeth ; anterior lateral 

 tooth short, acute, posterior elongate, compressed ; sinus narrow, elongated. 



Long. 2.25 ; Lat. 2.25 inches. 

 &quot; 57 ; &quot; 57 mill. 



Hab. North America, at Mazatlan, Mexico. (Cabinets of the British 

 Museum, the State of New York, Cuming and Gould.) 



