36 PALEONTOLOGY OF NEW JERSEY. 



and nearly all the localities of Miocene fossils throughout that part of the 

 State of New Jersey. They appear in the gray marls and in the limestone, 

 and also in the brown clay. 



HETEROMYARIA. 



Family AVICULID^E^Pteriidse. 



Genus PERNA Bruguiere. 



Perna torta. 



Plate v, figs. 12 and 13. 



Perna torta Say: Am. Jour. Sci. and Arts., 1st series, vol. 2, p. 38. 



Perna maxillata Conrad: Miocene Foss., p. 51, pi. 27: (non Lam.) 



Perna Conradi D'Orb. : Prodrome, vol. 3, p. 127. 



Isognomon torta (Say sp.) Conrad: Cat. Miocene Foss., Phil. Acad. Nat. Sci., 1862, p. 



579. 

 Melina torta (Say sp.) Meek: Check List Miocene Foss., p. 6. 



Shell very large, attaining a length of 7 inches, and a width of at least 

 3J inches. Form obliquely ovate, pointed at the beak, which is directed 

 forward Anterior and posterior margins subparallel and the lower maro-in 

 rather sharply rounded. Hinge line very oblique to the axis in the youno- 

 stages of growth, but less distinctly so in the larger individuals, and its 

 margin somewhat arched. General surface moderately convex. Liga- 

 mental area broad and as long as the shell, extending from the beak to the 

 posterior margin of the valves; vertically marked by ligamental grooves, 

 which extend the entire width and number from fifteen to near twenty 

 according to the size and age of the shell, and equal in size on the two valves 

 so far as can be seen in the best preserved individuals. Substance of the 

 shell, very thick, strongly lamellar, and highly nacreous. Muscular pits 

 deeply marked. 



I have never seen a specimen of this species which was anything like 

 entire, and the New Jersey specimens are always very imperfect. A single 

 partial cast, measuring about 3J inches in length, but almost entirely coated 

 with a thin layer of shell, gives nearly the whou* outline, and shows it to 

 correspond very closely to the form given by Mr. Conrad for a Maryland 

 specimen. It is a little more sinuate at the byssal opening only. The larg- 



