420 PROCEEDINGS OF THE ACADEMY OF [1881. 



stating that they all belong to but one species. Some of the 

 fossil specimens do not differ nearl}^ as much from tlie recent one 

 as the individual specimens of the latter do among themselves. 

 The statement of Say that the sides of the shell (/'*. Glintonius) 

 below the auricles slope much more rapidly downwards than in 

 G. Magellanicus is erroneous ; nor is there any appreciable differ- 

 ence in the character of the radiating striae. 



P. Peedeensis Tuomey and Holmes. N. Car. 



Plioc. Foss., p. 30. (See P. Peedeensis under Pliocene). 



The only authority I have (in addition to the statement of 

 Emmons) for stating that this species is found in the Miocene 

 deposits of North Carolina rests on an examination of one solitary 

 valve of a specimen marked by Conrad P. (Liropecten) Garolin- 

 fnsis (described in Kerr's Geol. Rep. of North Carolina, Appendix, 

 p. 18), which, as far as I have been able to determine, does not 

 differ essentially from the P. Peedeensis of Tuomey and Holmes. 

 The specific name, Garolinensis, is preoccupied by an Eocene 

 species. 



P. Rogers! Conr. Va, 



J. A.N. S., vii, p. 151. Mioc. Foss., p. 45. 



P. septemnarius Say. Md. ; Va. 



J. A. N. S,, iv, p. 136. Conr., Mioc. Foss., p. 47. 



I am inclined to believe that this species will be found to be a 

 mere variety of P. Jeffersonius Say ; want of a sufficient num- 

 ber of specimens with which to make the comparison has pre- 

 vented me from making a positive determination. 



?P. tricarinatus Conr. Va. 



A. J. Conchol., iii, p. 189. 

 = P. fraternus ? Conr. (See P. fratei'nus.) 



P. trioenarius Conr. Va. 



Proc. A. N. S., 1, p. 306. Mioc. Foss., p. 74. 



P. vicenarius Conr. N. Car. 



Proc. A. N. S., i, p. 306. 



Closely related to P. comparilis T. & H. 



P. Virginianus Conr. Va. 



Mioc. Foss., p. 46. 

 P. tenuis H.C. Lea. Trans. Am. Philos. Soc, ix, p. 246. 



Mr. Searles Wood (" British Crag Mollusca,'' Bivalves, p. 25. 

 Palseont. Soc. Reports, 1856), states that this shell somewhat 



