36 PALEONTOLOGY OF NEW JERSEY. 



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

 State of New Jersey. They api)ear in the gray marls and in the limestone, 

 and also in tlie brown clay. 



HETEROMYARIA. 



Family AVICTJLIl>^^ = Pteriidae. 



Genus PERNA Bruguiere. 



Perna torta. 



Plate V, figs. 12 and i;^. 



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



Perna mn.iillata Oourad : Miocene Foss., p. 51, pi. 27; (noii Lam.) 



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



Isognomon torta (Say sp.) Conrad: Cat. Miocene Foss., Pliil. Acad. Nat. Sci., 1S62, 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 

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

 forward Anterior and posterior margins subparallel and the lower margin 

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

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

 margin somewhat arched. Greneral surface moderately convex. Liga- 

 mental area broad and as long as the shell, extending from the lieak 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. ^luscular pits 

 deeply marked. 



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

 entire, and the New Jerse}' specimens are always very imperfect. A single 

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

 with a thin hiyer of shell, gives nearly the whole outline, and shows it to 

 con-espond \'ery 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- 



