68 CRETACEOUS GROUP 



bles Sowerby's Sanguinolaria undulata, tab. cxlviii, 

 fig. 2. 



Pholadomya. 



P. occidentalis, {§. G. M.) PL viii, fig. 3. 



Specific character. Oblong-ovate, anterior margin rounded, 

 ventricose ; posterior margin obtusely truncated, compressed ; 

 with twenty-five or thirty narrow, elevated, sub-tortuous costae, 

 having much broader, slightly concave, intervening spaces. 



Length, three inches ; breadth, about one-third less. 



I have examined five imperfect specimens in the Aca- 

 demy, all of which differ in the number and relative po- 

 sition of the costse. Mr. Featherstonhaugh possesses a 

 perfect cast. 



From the excavations of the Chesapeake and Delaware 

 canal. 



Pholas. 



P. cithara, (S. G. M.) PL ix. fi^. 10. 



Specific character. Ovato-cuneate, ventricose, cancellated, 

 with an oblique groove passing from beak to base. 

 Length, three-fourths of an inch. 



Obtained from the blue marl of Monmouth county, N. 

 Jersey, by Lieut. Mather, .to whose kindness I am in- 

 debted for an opportunity of describing and figuring it. 



Teredo. 



T. tibialis, (S. G. M.) PL ix, fig. 2. 



In the former edition I referred this species to T. an- 



& 



