LAMELLIBRANOHIATA OF THE LOWER MAELS. 119 



'this is the young of his C. pteropsis^ but I do not think it can be. He also 

 remarks that he has seen it at Haddonfield of a smaller size than the Mis- 

 sissippi specimens and "a great deal shorter proportionally," which seems 

 like straining a point to cover another species. The figure given by Mr. 

 Ccnirad (PI. I, Fig. 1) in the article above mentioned is also of a very dif- 

 ferent form from that originally figured as the t3'pe of the species. 



Formation and locality. — In the Lower Green Marls of the Cretaceous at 

 Monmouth, New Jersey. Mr. Gabb's specimen was from Hardeman County, 

 Tennessee, and is also cited by him from Eufaula, Alabama. Mr. Conrad's 

 specimen described under the same name was from Tij^pah County, Missis- 

 sippi. 



Crassatella Dela'Virareusis, Gabb. 

 For refeience,s auil duscriptiou see page 210. 



Mr. Gabb cites his tyj^e specimen as coming from the deep cut on the 

 Delaware and Chesapeake Canal, which would be the Lower Marl Bed, but 

 none of those which I have seen are from that horizon. 



Crassatella Moumouthensis. 



Plate XVII, Figs. 21 and 22. 



Crassatella Motimouthensis, Gabb. Jour. Acad. Nat. Sci., Phil., Vol. lY, p. 302, PI. 



XLVIII, Fig. 19. Meek, Geo!. Kept. N. J., 1868, p. 727. 

 Etea Monmouthensis (Gabb) Conrad. P. A. N. Sci., Pbil., 1876, p. 275. 



Shell of small size and moderately oblique; in the condition of a cast, 

 one-fourth longer than high, with moderately elevated beaks, which are 

 strong, broad, slightly incurved, and situated at about one-third of the length 

 from the anterior end. The hinge-plate has been strongly arched and of 

 •considerable width, especially on the anterior side of the beaks, with strong 

 and proportionally large teeth and a rather moderate ligamental pit. An- 

 terior end of the shell widest, round, and full ; basal margin strongly arched 

 and imperceptibly sinuate between the middle and the }X)sterior umbonal 

 angle. Posterior margin obliquely truncate and but little more than half 

 as high as across the beaks. Umbonal • angle sharp and very distinctl}* 

 •marked. Muscular scars strongly marked and of considerable size. 



