157 St. Maurice*;- and Claiborne Pelecypoda 157 



emarginate ; cicatrices not perceptible ; cavity of the shell deep in the su- 

 perior part — of the beak deep and angular ; inferior portion of the margin 

 finely crenulate. 



Diam Length i, Breadth 1.2, of an inch. 



A single valve of this interesting species has come into m}- possession • 

 It is the left one. Its beautiful form eminently distinguishes it. The ex- 

 terior portion of the valve is not perfect, and characters not observed on 

 this specimen may be, perhaps, found on perfect ones. 



In Claiborne material there is generally a great number of 

 Egcrella, with a very few large specimens. We have no inter- 

 mediate forms. Conrad's thick donacea with slightl}' incurved 

 anterior dorsal margin ma}^ be the young of this ; likewise some 

 of deGregorio's //^<u seem to have the form of the earlier por- 

 tions of triangiilata. 



Type. — No. 5096, Phila. Acad. Coll. 



Horizon. — Claiborne Eocene. 



Speci?ne7is figured. — Paleont. Mus. Cornell Univ. 



Locality. — Claiborne, Ala. 



Egerella subtrigonia L,ea. PI. 48, Figs. 14-16, a 



Egeria subtrigonia Lea, Cont. to Geol., 1833, p. 53, pi. i, fig. 22. 

 E. veneriformis Lea, ibid, p. 53, pi. i, fig. 23. 



Lea's original description. — Shell subtriangular, somewhat inflated, 

 inequilateral, polished, obtusely angular before and at top ; substance of 

 the shell thin ; anterior slope furnished with a small fold ; beaks slightly 

 elevated, pointed ; cicatrices perceptible ; cavity of the shell rather shal- 

 low ; inferior portion of the margin minutely crenulate. 



Diam. .2, Length, .3, Breadth .5, of an inch. 



There is a very close resemblance between this and the Bucklatidii, 

 and had there not been so much disparity in the size of the shell and thick- 

 ness of the valve, I should not have been disposed to separate them. The 

 valves of three specimens are before me. They are of the same size, and 

 have every appearance of being adults. 



Regarding veneriformis Lea remarks : 



This small species has a close resemblance to the last described. It 

 differs chiefly in size and in being more equilateral. It is very common in 

 this stratum. 



Lea evidently referred all the small specimens at Claiborne to 

 veneriformis, as he had only from one to three valves of the 



