46 PALEONTOLOGY OF NEW JERSEY. 



cular IdgIow the ears and a little straightened on the cardinal slopes. Valves 

 convex, slightly inequivalve and erect, or not perceptibly inequilateral. 

 Cardinal line about half as long as the greatest width of the valves, which is 

 a very trifle less than the height. Auriculations very unequal, distinctly 

 separated from the body of the shell. The posterior one is quite small and 

 ahke in each valve: anterior large, ribbed on each valve, and provided 

 with a moderately distinct notch below in the right one. Right valve most 

 convex, marked by seventeen to nineteen elevated radiating ribs, which 

 are somewhat flattened on the top and are marked by fine transverse stricE. 

 Interspaces narrow and deep. Many of the ribs of this valve become 

 duphcate below the middle of the valve. Left valve depressed, convex, 

 with narrow, sharply-elevated ribs, which are separated by much wider 

 interspaces, and are marked by compavatively distant elevated rugge. 

 Many of the wider interspaces have a thinner and smaller rib along their 

 middle below the center of the valve, corresponding to the duplicated ribs 

 of the opposite valve. 



On the interior of the valves the ribs are distinctly marked, but much 

 more strongly so along the margin of the shell. Cardinal Hue marked by 

 a single ridge on each side of the center nearly parallel to the hinge line 

 in the left valve, with corresponding grooves in the right. Ligamental pit 

 well marked. 



This shell appears to be a true Peden in its characters, but has been 

 referred to the group Clilamys Bolton, by Ferd. Stoliczka, probably from 

 the inspection of figures only. The specimens seen are mostly in the 

 condition of complete or partial casts in the marl, but at Freehold, N. J., 

 occur with the shell substance preserved, but of so fragile a character that 

 it is with difficulty they can be cleaned and examined, and then with the 

 beaks usually broken. 



Formation and locality, — In the Lower Green Sand at Monmouth, Free- 

 hold, Burlington, Arneytown, etc., in New Jersey. The entire shells figured 

 were obtained at Freehold by Miss F. M. Hitchcock, who kindly loaned 

 them for illustration and description. 



