1881.] NATURAL SCIENCES OP PHILADELPHIA. 451 



A. incile Say (Anadara). Va. ; N. Car. 



J. A. N. S., iv, p. 139. Conrad, Mioc. Foss., p. 56. 

 Emmons, Geol. N. Car., 1858, p. 284. 



A. lienosa Say (Scnpharca). N. Car. 



American Conchology, PI. 36, fig. 1. 

 Emmons, Geol. N. Car., p, 384. 



This species appears to be undistiuguishable from tlie recent 

 A. Floridana Conr., the specific name of wliich will consequently 

 have to be replaced b}^ that of Say's species, which has priorit}'. 



A. limula Conr. (Noetia). Va. : X. Car. 



Tert. Foss., 2d ed., p. 15 ; Mioc. Foss., p. 60. 



A. Marylandicus Conr. (Barbatia). Md. 



Mioc. Foss., p. 54, as Byssoarca. 



A. plioatura Conr. (Scapharca). N. Car. 



Mioc. Foss., p. 61. 



A. improcera Conr. Mioc. Foss., p. 60 (young). 

 A. lirieolata Conr. Mioc. Foss., p. 61. 

 A. (equicostat.a * Conr. Mioc. Foss., p. 60. 



* I have seen no authenticated specimens of this last, but feel satis- 

 fied that it is no other than tlie A. lineolata, with the description of which 

 it thoroughly agrees. A specimen of A. lineolata, so marked by Conrad, 

 is the one from which the figure of A. mquicostata in Mioc. Foss. ^Pl. 31, 

 fig. 6) has been taken. 



The A. plicatura (I have retained the name as best illustrative 

 of the specific character of the fossil) differs principally from the 

 recent A. transversa of Say in being a less capacious shell, and 

 in having the posterior slope much less distinctly angulated or 

 carinated. The young shells of both species appear to be undis- 

 tiuguishable from each other, and although there are sufficiently 

 well-marked characters separating the full grown, I have but little 

 hesitation in believing that the coast shell of the present day 

 (which appears also as a post-Pliocene fossil) is only a derivative 

 from the fossil form. The A. plicatura recalls the A. diluvii, 

 from the European Miocene deposits. 



A. propatula Conr. (Barbatia). Va, 



Proc. A. N. S., i, p. 323 ; Mioc. Foss., p. 61. 

 ? Area hians Tuomey and Holmes. Plioc. Foss., p. 34. 



The figure of this species in the " Pleiocene Fossils," very 

 closel}' resembles the type specimen of Conrad's A. propatula^ 

 and I have but very little doubt (although I have not seen an 



