MIOCENE MOLLUSCA AND CRUSTACEA. 45 



SCAPHARCA SUBROSTRATA. 



Plate VI, Figs. 11-13. 



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



Nat. Sci. Phil., 1887, pp. -100 and 402. 

 Scapharca subrostratii Courad: Proc. Acad. Nat. Sci. Phil. 1862, p. 580; Meek, Check 



List Mioceue Foss., p. fi. 



"Ovate, pvot'oundly 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 extremitv. 



"A variable shell. The young are 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, X. J.; and noticed bv 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 ri1)s render it easy 

 of determination. One of the frag-ments 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 cjitite 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 "longitudinallv 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 mid Jocaliti/: In the deep well-lioring at Atlantic City, N. J. 

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



