570 



SHELLS AND SHELL-FISH. 



PART II. 



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 4- ; lateral teeth 4, short, 

 thick, obtuse ; fluviatile and marine. {fig.W^.n.^ 

 C. Siimatrensis. Sow. Gen. 1 — 4. 



Megadesma Bowdich.* Shell thick, trigonal, nearly 

 equilateral ; cardinal teeth 4t ', lateral teeth obsolete ; 

 hinge very thick ; ligament external. (^fig.llQ. 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. 



EBYCiNAf Lam. Shell always transverse, generally 



cuneate, but rarely equilateral ; both valves closing ; 



cardinal teeth ^, between which is the ligament ; 



lateral teeth ^y one of which is lengthened. 



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



(/5r. 118. d,e.) 



* Gttlathcea of Lam. 



t This name should be chanjjed, havinjj been previously applied by 

 Fabricius to a large family of lepidopterous insects. Eiijx may be used, a& 

 preserving the same mythological idea. 



