PLATE XLII. 



PAGE 



Figs. 1, 2a, 2b. Ckassatellites aquiana (Clark) 181 



1. Dorsal aspect of type specimen. Aquia Creek. 

 2a. Exterior of! left valve of the same individual. 

 2b. Exterior of right valve of the same. 



Fig. 3. Ckassatellites alta (Conrad) 182 



Exterior of specimen. Hardesty. 



Figs. 4, 4a. Crassatellites sp 183 



4. Exterior of right valve. Clifton Beach. 

 4a. Interior of the same. 



Fig. 5. AsTARTE MARYLAKDiCA Clark 183 



Exterior of left valve of type specimen. Upper Marlboro. 



294 



