1(10 PALJEONTOLOGY OF NEW YORK. 



PtERINE.V CONSIMILIS. 



I't.ATK XVI, KKiS. 1. 2, S, !l, 11 ; ANI> I'l.ATK I.XXXIV, KKJ. 23. 



Plerlnin ciinxliiiUi.1, IIai.i.. Piil. N. V., vol. v, jit. 1. Pliitcs ami Kxphiniitions : PI. l.'i, tip*. 1, 2, S. it, 11. 



Jan.. 18S8. 



Shki.i, large, sub-vli(iinlii)i(l;il, neai'ly orbicular: k'ligth greater than tlic licidit : 

 margins regularly curved, moderately produced on the posterior end. 



Left valve convex al)0ve, depressed-convex below. Right valve romcx on 

 the umbo, tlat or slightly concave below. 



llinge-line straight, length equal to or a little greater than the length ul' 

 the valve. 



Beak acute, anterior, inc^lined slightly forward, not rising altove the hinge. 

 Umbonal region prominent hut not strongly liinittMl, sulttending more than a 

 right angle. 



Ear small, liniited by the a1inn)t slope of the umbo, which becomes a dis- 

 tinct sulcus in till' right valve; margin convex (except in the by.ssal sinus); 

 extremity rounded. Byssal sinus not distinct. Wing broad, triangular, 

 undefined, much extended ; margin concave ; extremity acute. 



Surface of left valve marked by numerous flattened, slender, filiform rays, 

 with broad, flat interspaces, which are marked by one or two, more or less dis- 

 tinct, finer rays. The radii are often undulating, and become obscure towards 

 the base. The cardinal expansions are correspondingly inaiked. Fine, closely 

 arranged, inconspicuous concentric striae cross the sm-face. The wings of 

 both valves are similar in surface characters. Tlic body of the right valve 

 shows the concentric striaj, with obscure indications of rays. 



Ligamental area broad, marked by fine parallel grooves the entire length. 

 Lateral teeth two, strong, converging. Cardinal teeth preserved as three short 

 plications under the beak of the left valve. Pallial line simple, originating 

 anterior to the beak, continuing nearly parallel to the margin of the valve, 

 recurving and terminating in a large muscular scar on the post-cardinal .slope 

 juljacent to the wing. 



A left valvi' has a length of 02 mm., height 49 mm., hinge-line about 50 



