MIOCENE MOLLUSCA AXD CRUSTACEA. 31 



the ribs and on their sides. This feature becomes very conspicuous on the 

 larger specimens. Besides this, the lower valve is much more depressed 

 or flattened than the upper. The number of ribs on the more convex valve 

 is sometimes seventeen or even eighteen, showing considerable variation. 

 I have not seen any very large individuals from the New Jersey localities, 

 and few of more than 1% inches in diameter. Some of the casts from the 

 brown clays, however, indicate shells much larger than this, and some 

 fragments of valves from near Shiloh, in the collection at Rutgers College, 

 indicate shells of fully 4 inches in width, but no specimens showing more 

 than one-sixth part of the entire valve have been collected. 



The species bears some resemblance to Pecten Jeffersonius Sav, but is 



t/ * 



very readily distinguished by the more numerous and smaller ribs and by 

 their squamose, almost spinose striae. 



Formation and localities: The New Jersey examples, all quite frag- 

 mentary except the very young individuals, are from the gray Miocene 

 marls near Shiloh and Jericho, and as casts from the brown marly clays 

 near the same places in New Jersey. The species is quite common and of 

 larger size in the Miocene at Yorktown, Petersburg and vicinity, in Vir- 

 ginia; it also occurs in South Carolina, 



PECTKX VlCENAKirs? 



^ot figured. 



Pecten vieenarim Conrad: Proc. Acad. Nat. Sci. Phil., vol. 1, 1st scries, p. 306; op. 



cit. 1862, p. 582; Meek, Check List Mioc. Foss., p. 4. 

 Pecten vicenarim Con: Heilprin, Proc, Acad. Xat. Sci. Phil., 1887, pp. 400 ami 402. 



" Suborbicular, inequi valve, the upper valve ventrieose, the inferior 

 plano-convex; ribs about twenty, somewhat flattened on the back; ribs of 

 the superior valve narrow and more distant than those of the inferior valve; 

 surface of both with crowded, regular concentric wrinkles; ears equal, mod- 

 erate in size, sinus of inferior valve not profound." (Conrad.) 



A number of small fragments of a pectenoid shell of small size, which 

 were obtained from the well boring at Mr. L. Woohnans, at Atlantic Citv, 

 form the basis for the citation of the above species as a probable New 

 Jersey shell. I should consider the fragments as pertaining to two distinct 



