370 



SHELLS AND SHELL-FISH. 



teral ; cardinal teeth small; lateral teeth ~, long, 

 compressed; ligament external, {fig. II9. &.) 

 C. rivicola. Sow. Man. f. 111. 



Cyrena Lam. Shell thick, transversely ovate, nearly 

 equilateral ; cardinal teeth ^ ; lateral teeth |-, shorty 

 thick, obtuse ; fluviatile and marine, (fig. II9. «•) 

 C. Sumatrensis. Sow. Gen. 1 — 4. 

 Megadesma Bowdich.* Shell thick, trigonal, nearly 

 equilateral ; cardinal teeth 4^ ; lateral teeth obsolete ; 

 hinge very thick; ligament external. (figAlQ- d') 

 M. radiata. Sow. Man. f. 115. 

 Gnathodon Gray. Shell transversely obovate, in- 

 equilateral ; bosses thick, prominent, remote ; car- 

 dinal teeth i ; lateral ", ; cartilage internal, placed 

 by the side of the cardinal teeth. 



G. cuneatus. Sow. Man. f. 83. 



CuMiNGiA Sow. Shell transversely obovate ; hinge 

 with a spatulate cavity filled by the cartilage ; car« 

 dinal teeth -}, very small ; lateral teeth ^ ; marine : 

 leading to Erycina, and representing Amphidesma. 

 C. mutica. Sow. Man. f. 87. 



Erycina t Lam. Shell always transverse, generally 

 cuneate, but rarely equilateral ; both valves closing ; 

 cardinal teeth ^, between which is the ligament; 

 lateral teeth ^, one of which is lengthened, 

 striata. Sow. Gen. f. 2. plebeja. lb. f. 3. 



(/^. 118. d,e.) 



* Galathcea of Lam. 



t This name should be changed, having been previously applied by 

 Fabricius to a large family of le])idopterous insects. Eryx may be used^ as.- 

 pyeserviiig the same mythological idea. 



