331 Bulletin 5 61 



155 



The species of this genus are very closely allied 

 to each other, and at the same time they exhibit 

 so few characters, that it is with difficulty that 

 some of them are determined. The present seems 

 to differ from either of those already described. 

 In the collection of the Academy are two frag- 

 ments of Dentalia very closely allied to this spe- 

 cies, which were obtained by Mr. A. Jessup in 

 New Jersey ; but their imperfect state do not 

 justify me in deciding upon a fact so important to 

 geology as their specific identity. 



[J. A. N. S., Phila., ist Ser., Vol. IV, 1824.] 



