^4 PALEONTOLOGY OF NEW JEESEY. 



are slightly unequal and sometimes very decidedly so. The form of the 

 byssal opening is also peculiar, being broadly oval and regular instead of 

 a long narrow slit, as is usual. 



Formation and locality.— Th^ only specimen which I have seen is an 

 internal cast from the collection of the Academy of Natural Sciences of 

 Philadelphia, and is marked ^^Cibota, n. sp., Burhngton Co., N. J." 



Cibota mnltiradiata. 

 Plate XI, Figs. 21 and 22. 



Area f mnltiradiata Gabb. Proc. A. N. Sci., Phil., 1860, p. 95, PL II, Fig. 1. Synopsis, 



p. — . Meek, Check-list, p. ~. Geo!. Snrv. :t^. J., PI. LXVIII, p. 725. 

 Cibota multiradiata Gabb. 

 Oomp. C. cretacea Conrad, Am. J. Conch., Vol. Y, p. 97, PI. IX, Fig. 21. 



Shell small, the type specimen measuring only about five-eighths of 

 an inch in length. Valves transverse, very ventricose, with a wide curved 

 cardinal area, and moderately prominent, distant beaks situated at about 

 one-third of the length from the anterioi: end Posterior end obhquely 

 truncate, longest below ; anterior end narrowly rounded, very gradually 

 receding from the extremity of the hinge; basal line gently convex through- 

 out, the margins of the valves shghtly gaping just anterior to the middle of 

 their length. Hinge-hne nearly as long as the shell below, and on the cast 

 very slightly curved. Muscular scars small and faint, the posterior one 

 bounded by a constriction on the cast which leaves a furrow extending from 

 the margin of the valve to near the beak. On the margin of the cast there 

 occurs minute crenulae which indicate the existence of strong but closely 

 arranged radiating plications on the surface of the shell. 



The general form of this cast is like that of Nemoarca cretacea Conrad, 

 but the specimen is somewhat larger than any of those which I have referred 

 to that species, and the beaks are more distant, while that species is not 

 emarginate on the base, being without the byssal opening so distinct ii: 

 this one. 



Formation and localitij. — The only individual known is in the collection 

 of the Academy of Natural Sciences, Philadelphia, and is labeled as coming 

 from MuUica Hill, New Jersey, which would place it in the Lower Marl 

 Beds. 



