54 CONTRIBUTIONS 



in being more equilateral. It is very common in this 

 stratum. 



E. ovalis. Plate 1. Fig. 24. 



Description. Shell transversely elliptical, compressed, 

 very inequilateral, furnished with two lamellar lateral 

 teeth, covered with minute concentric striee, which, termi 

 nating at the anterior slope, are replaced by larger ones 

 which there interlock ; substance of the shell very thin ; 

 beaks small and pointed ; cavity of the shell very shallow ; 

 margin entire. 



Diam. ,1, Length .2, Breadth .4, of an inch. 



Observations. This beautiful little species differs much 

 from the four last described. The cardinal teeth are the 

 same, but this is furnished with a small lamellar tooth 

 diverging on each side of the cardinal teeth. The termi 

 nation of the concentric striae, which pass from the pos 

 terior slope, interlocking with those which cover the 

 anterior slope, is very remarkable. 



E. plana. Plate 1. Fig. 25. 



Description. Shell scaleniform, very compressed, trans 

 verse, very inequilateral, smooth and shining, furnished 

 with two lamellar lateral teeth ; substance of the shell 

 very thin ; beaks very small and pointed ; cavity of the 

 shell extremely shallow ; margin entire. 



Diam. nearly .1, Length .2, Breadth 7-20ths. of an inch 



