204 



THE SILVER SHELL. 



Thracia curta, Conr., Thra'-shi-a cur'-ta. In form 



and marking's its shell resembles 



Fig. 



151, but it is 



somewhat oblong and wrinkled at the rear end of the 

 valves. Ligament external, hinge-teeth small, pallial 

 sinus shallow, length from an inch to two inches. 

 Periploma ctrgentaria, Conr., Per-i-plo'-ma ar-gen- 

 This is a pretty species, easily rec- 

 ognized by its peculiar 

 spoon-like hinge-teeth. Ob- 

 long, beaks near the posterior 

 end, pallial sinus small, right 

 valve bulged, left one flat- 

 tened. White, smooth, with 

 Fi s- I75 - fine lines of growth, silvery 



within. Length an inch or two; southern. 



Corbiria luteola, Cpr. , Cor'-bu-la lu-te'-o-la. Shell 

 shaped somewhat like a small Donax, yellowish, 

 marked with lines of growth. Ligament internal, in 

 a small pit;- pallial sinus small. Valves rather thick, 

 incurved at the edges, angled at one corner. The 

 length of this southern species is only three-eighths 

 of an inch. 



