LAMELLIBEANCHIATA OF THE LOWER MARLS. 109 



Formation and locality, — From the micaceous clay of the Lower Marls at 

 Haddonfield, N. J. Mr. Gabb cites his specimen from Burlington County, 

 New Jersey, an extremely large locality for so small an object. 



Nuculaua compressifrous. 



Plate XI, Fig. 9. 



Yoldia compressifrons Conrad. 



Leda protexta Gabb. J. A. N. S., Phil., K. S., Vol. lY, p. 397, PL XLYIII, Fig. 36, ]S"ot 

 X. protexta Gabb, Ibid., p. 303, PL XLYIII, Fig. 23. 



Shell of medium size, barely exceeding half an inch in length in the 

 largest individuals observed. Outline elliptically cuneate and moderately 

 ventricose. Posterior end nearly tw4ce as long as the anterior, and narrow^ 

 but not exactly pointed, the extremity being slightly rounded. Anterior 

 end broad. Beaks prominent and comparativel)^ large ; basal line gibbous 

 opposite the beaks and imperceptibly sinuous just forward of the posterior 

 extremity of the shell. Escutcheon narro\V, forming a depressed line along 

 the postero-cardinal border. Surface of the shell smooth and usually pol- 

 ished, although occasionally showing regular concentric lines. Hinge show- 

 ing eight to ten teeth on the anterior end and about fifteen on the posterior 

 side. Teeth short. Ligamental pit very small, if observable at all. 



It is extremely difficult to draw comparisons betw^een this and othei 

 forms of the genus. Among New Jersey species it may be distinguished by 

 its broad form and smooth surface. The larger individuals of the species 

 were in the collection of the Academy of Natural Sciences labeled iYw- 

 culana protexta Gabb, Ripley group, Haddonfield, N. J., apparently in Mr. 

 Gabb's own handwriting. They certainly are not identical with the cast 

 of that species originally used by Mr. Gabb and figured in the Journal of 

 the Academy of Natural Sciences, Vol. IV, PI XLVIII, Fig. 23. The smaller 

 specimens were separated in a tray by themselves and labeled Yoldia com- 

 pressifrons Conrad, Haddonfield, N. J., but they only differ in size, and it 

 is possible they may only be the young of the same shell wdth the Prince- 

 ton specimen figured as N, protexta Gabb. 



Formation and locality, — In micaceous clay of the Lower Marl Beds at 

 Haddonfield, New Jersey (collection of Academy of Natural Sciences of 

 Philadelphia. 



