MIOCENE MOLLUSC A AND CRUSTACEA. 51 



I havje not been able to compare these New Jersey specimens with 

 authentic specimens of Nucula obliqua of Say, so can not say positively 

 wherein it differs. The figures given by Mr. Conrad of that species would 

 answer equally well for many of the larger individuals of this one, and I 

 presume it may be from those figures that Mr. Heilprin made the identifica- 

 tion cited above. Mr. Conrad remarks under his description of N. obliqua, 

 in his Miocene Fossils, p. 57, that it may be a variety of the recent N. prox- 

 imo,, which, judging from his figures, I should think more than probable. 



Localities : It occurs in fair numbers at Shiloh, Jericho, and near Bridge- 

 ton, N. J. 



Genus YOLDIA Moller. 



YOLDIA LIMATULA. 



Plate vn, figs. 11 aiid 12. 



♦ 



Nucula UmatuH Say: Am. Conch., PL xn; Tuoiney aud Holmes Pliocene Foss. S. Car., 



p. 52, PL xvil, Fig. 3; Conrad, l\lioc. Foss,, p. 57, PL xxx, fig. 4. 

 t Nucula Icevis Say: Jour, Acad. tfat. Sci., 1st ser., vol. 4. p. 141, PL x, fig. 5. 

 f Yoldia Icevis (Say) Conrad: Proc. Acad. Nat. Sci., Phil., 1862, p. 581,- Meek, Check 



List Miocene Foss., p. 5. 

 Yoldia limatula (Say's sp.) Heilprin, Tert. Geol. U. S., p. 8; Proc. Acad. Nat. Sci. 

 Phil., 1887, pp. 397, 398, aud 402. 



The specimens of Yoldia which are found in the Miocene marls of New- 

 Jersey present to me too many similarities and too few variations from the 

 living species, Y. limatula of Say, to be considered as specifically distinct, 

 or even as a variety. I have not seen any specimens of it which present 

 quite the features of the hinge line shown in Mr. Say's figures of Nucula 

 Icevis, 1 from any of the American localities, the pectination always termi- 

 nating much earlier than there represented. Still that may be an error of 

 Say's illustration only, and as the feature is not mentioned in his descrip- 

 tion, it must remain in uncertainty. The only differences which I can find 

 between the New Jersey fossil specimens and the recent ones of the same 

 size, from along the coast near New Jersey, are, that in the fossil form the 

 valves* are perhaps a little more convex; a trifle more slender posteriorly 

 and a very little more recurved than in the living ones. These I do not 



i Vol. 4, 1st series of the Jour. Acad. Nat. Sci. Phil, 



