30 CONTRIBUTIONS 
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> ’ f 
E. rotunda. Plate 1. Fig. 17. 
Description. Shell rotund, compressed, angular above, 
subequilateral, minutely and concentrically striate ; sub- 
stance of the shell thick ; beaks elevated, pointed; cica- 
trices deeply impressed, several visible in the centre of the 
cavity of the beaks; cavity of the shell shallow, rugose, 
cavity of the beaks subangular; margin entire. 
Diam. .3, Length .9, Breadth .9, of an inch. 
Observations. The resemblance in outline between this 
species and the nana, hereafter to be described, is very 
creat. It may be distinguished, however, from it by its 
finer concentric striz, and its larger size. The nana is 
always more oblique. The figure represents*the usual 
size, but it is sometimes found one third larger. 
b] 
E. inflata. Plate l. Fig. 18. 
Description. Shell subrotund, rather transverse, inflat- 
ed, subequilateral, very finely and concentrically striate ; 
substance of the shell very thin ; beaks rather elevated ; 
posterior slope furnished with an indistinct fold. Cica- 
trices scarcely perceptible ; cavity of the shell much ex- 
cavated, of the beak deep and rounded ; margin entire. 
Diam. .2, Length 7-20ths, Breadth 7-20ths, of an inch. 
Observations. Differs from the rotunda in being more 
transverse, in the substance of the shell being much thin- 
