MIOCENE MOLLUSCA AND CRUSTACEA. 43 



erated by the subsequent deuosit from the interior by additional growth 

 of the shell. 



Localities: The only specimens seen from New Jersey are from Shiloh 

 and vicinity. The species is abundant at many localities in Maryland, 

 Virginia, and in North and South Carolina, Collection at Rutgers College 

 and National Museum. 



Arca (Scapharca) callipleura. 



Plate vi, figs. 8 and 9. 



Arca callipleura Conrad : Miocene Foss., p. 54, PI. xxix, fig. 2. 

 Scapharca callipleura Conrad: Proc. Acad. Nat, Sci., Phil., 1862, p. 579. 

 Scapharca callepleura (Conrad) Meek : Check List Mioc. Foss., p. 6. 



" Shell subtrigonal, profoundly ventricose, thick, posterior area flattened 

 and very wide; posterior end oblique, emarginate; ribs little elevated, flat- 

 tened, with an impressed line in the middle of each, and another fine line 

 on each side of the central one; the ribs are beautifully granulated; beaks 

 very prominent and distant; inner margin with narrow very prominent 

 teeth." 



Mr. Conrad states that of this species he has seen but a single valve; 

 it therefore might be considered a rare species. Still among the specimens 

 obtained in the well boring at Mr. L. Woolman's, at Atlantic City, quite 

 a large fragment occurs which can not be referred to any other than this 

 shell, and at the same time leaves scarcely any doubt that it pertains 

 to this species. The fine line on each side of the medial impressed line of 

 the ribs can not be detected, but the shell ha^> been subject to some action 

 in the bed, so as to leave the impress of the grains of sand on the surface, 

 and thus obscure any finer markings which may have existed.' I have 

 figured the fragment as perfectly as it will permit, and I think it leaves no 

 doubt as to its relations to the figure given by Mr. Conrad, and also 

 copied on the plate here. 



The specimen belongs to the Academy of Natural Sciences at Phila- 

 delphia. 



