f)8 PALEONTOLOGY OF NEW JERSEY. 



agree very well indeed with liis .sj^ecies C. protrada. '^Phei-o is one feature of 

 this species in which it appears to differ materially from C. protracta, viz, 

 the "dilation" of the extremity of the three large ribs of the posterior end. 

 Anion;^- tile six-cimens which 1 have examined this is generally a raai'ked 

 feature. The three ribs which occur on the innbonal ridge jiroject beyond 

 the others so as to })r(>loug the margin oi' the valve; and the tlu'ee, or gen- 

 eralh' fotu-, small ribs above them, on the posterior slope, contract the pos- 

 terior truncated uiargin by their smaller size. The disk of the valves is 

 usually broadly sinuate or depressed from behind the beak to the base of the 

 shell, altliough the I'ibs gradually increase in size from the most anterior to 

 the one which runs along the umbonal ridge. The surface of the ribs are 

 ver^- strongly crenulated by the coarse concentric strije of growth, and near 

 the posterior cardinal border are often pi'olonged into short, recurved, spi- 

 nose processes. In the older specimens the inner margin is strongly den- 

 ticulated and the muscular imprints strongly marked. The hinge plate, 

 however, is rather slight and narrow. 



Localities: In New Jei'sey the species has been found at Shiloh, Jericho, 

 and Bridgeton. At Jericho it does not appear to be uncommon, although 

 seldom of large size. From the collections of the National Museum prin- 

 cipally. A few also from those at Rutgers College. 



Carditamera aculeata. 

 Plate. IX, tigs. 7 and 8. 



(Jnrtlitamcra aculeata Conrad: Proc. Acad. Nat. Hci. Phil., 1862, p. .585; Am. Jour. 

 Coiub., vol. 2, J). 73, PI. IV, tig ">; Meek, (Jheck List Miocene Foss., p. 7; Heil- 

 l)rin,Tcrt. Geol. U. S., p. 8; Miocene Moll. New Jersey, Proc. Acad. Nat. Sci. 

 I'hil., 1887, pp. 397, 398, and 403. 



Conip. ('. arata Con. in the yonng stages of growth. 



In Conrad's original description of this s[)ecies he says: "Trapezoidal; 

 umbonal slope inflated; base emarginate; ribs on anterior side crenulated, 

 on the anterior side subs])inose." His second descri])tion is as follows: 

 "Tra])c/,oidal iiie(|iiilateral; iiinboiial slope ventricose; l)ase emarginate in 

 the middle; disk contracted in the middle; ribs very large over the umbonal 

 slope; anterior ribs crenulated; the larger ribs and the dorsal submargin 

 witli i)rominent scales." 



