LAMELLIBRANCHIATA OF THE LOWER MARLS. 75 



of tliat one, however, have been remarkably flat, and present an extremely 

 shallow cavity, as in fact do the largest shells, while this one, although so 

 very small, is almost half as thick as high, which is a remai'kable difference 

 for shells of this character. Besides, the entire features as presented by 

 this cast, are those of a perfectly formed adult individual. 



Formation and locality. — In the Lower Green Marls at Freehold, New 

 Jersey. 



Geuus INOCERAMUS Sowerby. 



luoceramus Barabiui. 



Plate XV, Figs. 3-.5. 



luoceramus Barabini Mortou ?. Synopsis, p. 62. 



I. Cripsii, var. Barabini (Mort.). Meek, luvert. PaL Geol. Surv. Territ., p. 



— , PI. XII, Fig. 3. 

 /. Barabini ( :\Iort.). Wliitf., Pal. Black Hills of Dakota, p. 398, PI. VII, Fig. 



7, and PI. IX, Fig. 8. 

 Xot Inoceramits barabini of authors generally. 



Shell of only moderate size, transversely ovate or elliptical, with mod- 

 erately to prominently convex valves. Beaks large, only slightly project- 

 ing beyond the line of the hinge, and situated near the anterior end. Hinge- 

 line two-thirds as long as the shell, and rajoidly rounding at the posterior 

 extremity into the posterior margin, which is more broadly rounded than 

 the anterior extremity. Basal line gentlv and somewhat gradually arcuate, 

 but more rapidly curving upward near the anterior part. Surface of the 

 shell marked by regular concentric, rounded undulations parallel to the 

 margin of the valve, and separated by concave interspaces. Near the 

 outer limits of the valve the undulations become more irregular, as if 

 taking on old-age characters. 



The specimen used in the above description is an imperfect cast of a 

 right valve. The undulations are somewhat narrower than are those on 

 specimens recognized as of this species from the Upper Missouri and Black 

 Hills regions, but the general form of the shell is nearly the same, except, 

 perhaps, in being a little less gibbous and a little higher, perhaps the result 

 of flattening. In the narrower undulations it resembles Dr. Toumey's 

 specimens of I. jiroximits, but the valves are too ventricose for that species 

 and the outline not nearlv as circular. There mav be some dou])t as to 



