24 PALiEONTOLOGY OF NEW JERSEY. 



beak compressed, equilateral; beaks prominent, oblique; anterior ventral 

 margin roimded, posterior obliquely truncated ; posterior end truncated and 

 situated much above the line of the base (cast)." In comparison he says, 

 "this sj)ecies is nearly allied to, if not identical with, Astarte Triasina, 

 Dunker." 



I have not been able to obtain specimens agreeing with the above descrip- 

 tion, nor to find tlie type specimen used by Mr. Conrad. The form of the 

 shell would indicate that it belonged to the genus Astarte, but be3ond that 

 there appears to be no real evidence of its generic relations more than there 

 is to other species found in these clays. The outline of the shell might 

 suggest that it was a young individual of what 1 have herein called Gna- 

 thodon tenuidens, but the apparent want of gibbosity would not agree. So 

 for the present at least the species will have to be left as it is. 



Formation and locality. — Mr. Conrad cites it as coming from the "ash- 

 colored clay near Washington, Middlesex County, New Jersey." 



CYPRINIDiE. 



AMBONICARDIA, n. geii. 



Shell bivalve, large and heavy, triangularly-rhomboidal in outline; 

 beaks anterior, large, ponderous, and enrolled. Body of the valves sulcated. 

 Ligament external, large, resembling that of Unio. A large well-marked 

 lunule occurs beneath the beaks. Hinge only partially known, but pro- 

 vided with a strong tooth anterior to the center in the left valve; posterior 

 teeth probably obsolete. Anterior muscular scar deep, placed well anterior; 

 pallial line simple. Exterior coated with an epidermis. Type A. Cooki. 



The shells for which the above name is proposed very closely resem- 

 ble that section of the genus Unio which is typified by U. pyramidata, 

 common in the Ohio and Mississippi watershed, differing externally only 

 in having a strong lunule. They are probably closely related to the 

 genus Veniella and allied Isocardias; but they differ so strongly from 

 any of them, that it appears unnatural grouping to place them in any of 

 the established genera. They are as near Veniellicardia, Stoliczka, as to 

 any one, but so far as I can judge from a large number of imperfect speci- 

 mens, there seems to have been no lateral teeth, or any thickness of shell 



