PSEUDODON. 



151 



less distinct and placed a little more posteriorly ; nacre light 

 salmon, iridescent. 



Long. 32, lat. 53, diain. 13 mm. 



Huh. Pegu. 



Comparing the present variety with what must be considered 

 the typical form of F. peguensis, the author makes the following 

 observations : — " .... uniformly more depressed, lighter coloured; 

 more regularly rhombic in form, and of less size ; but the most 



2 



Fig. 9. — 1 tS: 2. Vscudodon (T.) pcguensis (Ant. "J vor. curvata, Preston. 

 (Type.) Nai. size. 

 3. Hinge and muscular scars of same. 



prominent difference consists in the beautiful creuulose striae of 

 the present species, which are densely crowded over the whole 

 surface of the shell, while M. [P.^ peguensis is remarkably smooth 

 over all except the posterior .'^lope, and tliere the rugose folds are 

 broader and less numerous than in M. [P.] crehristriata ; the lines 

 of growth are also more numerous in M. [P.'] peguensis, generally 

 about 8, while crebrisiriaia has rarely more than 3. 



