MIOCENE MOLLUSCA AND CRUSTACEA. 45 



SCAPHARCA SUBROSTRATA. 



Plate vi, Figs. 11-13. 



Area subrostrata Conrad: Mioc. Foss., p. 58, PI. xxx, fig. 7; Heilprin, Proc. Acad. 



Nat. Sci. Phil., 1887, pp. 400 and 402. 

 Scapharca subrostrata Conrad: Proc. Acad. Nat. Sci. Phil. 1862, p. 580; Meek, Check 



List Miocene Foss., p. 6. 



" Ovate, profoundly ventricose, ribs about thirty, little prominent, flat, 

 longitudinally sulcated in the middle, and with from one to three impressed 

 lines on some of the ribs ; the lines more numerous and distinct towards the 

 umbonial slope; posterior side cuneiform, extremity acutely rounded or 

 subangular; umbonial slope rounded below, angulated on the umbo; pos- 

 terior slope depressed, flattened; beaks distant, summits prominent; series 

 of cardinal teeth narrow, inflected towards the posterior extremity. 



"A variable shell. The young aire proportionally more elevated, and 

 not produced posteriorly, and the left valve has crenulated ribs. It is 

 slightly inequivalved. Generally occurs in single valves." (Conrad Mio- 

 cene Fossils.) 



Two small fragments of this species have been obtained from the well- 

 boring at Atlantic City, N. J. ; and noticed by Prof. A. Heilprin. The speci- 

 mens preserve enough of the surface plications to make their specific identity 

 quite sure, as the character of the flattened striated ribs render it easy 

 of determination. One of the fragments is from the middle portion of the 

 basal margin of a valve and the other from near the anterior end of a left 

 valve, and shows quite well the crenulations of the ribs spoken of in Mr. 

 Conrad's descriptive remarks in the second paragraph quoted above. The 

 ribs are flattened on top with three longitudinal depressed lines on each, the 

 middle one of which is deeper and wider, giving the feature which Mr. 

 Conrad describes as " longitudinally sulcated in the middle." The depres- 

 sions between the ribs are not more than half as wide as the ribs, and are 

 also flattened in the bottom. 



Formation and locality : In the deep well-boring at Atlantic City, N. J. 

 From the collection of the Academy of Natural Sciences at Philadelphia. 



