210 PALEONTOLOGY OF NEW JERSEY. 



at about the anterior third of the length of the shell, and are somewhat in- 

 curved and appressed. Anterior end of the casts short, rounded, but not 

 wide; posterior end much broader, almost squarely truncate or a Httle 

 oblique to the axis, being longest at the posterior basal angle; basal margin 

 broadly curved. Disk of the valves convex, most prominent near the um- 

 bones, and with a prominently angular umbonal ridge and abrupt posterior 

 umbonal slope. Muscular scars proportionally strong and of moderate size; 

 pallial line strongly marked. 



I at first thought these casts might be the same specifically as that 

 described by Conrad as C. curta, above cited, although he doubtfully sup- 

 posed his specimen to have come from Virginia. The form is so closely 

 similar, although in a diff^erent condition, that it seems difficult to separate 

 them. The specimens are subject to but little variations among them- 

 selves in form. They appear a little longer or shorter, and with a more or 

 less sharply angular umbonal ridge. On a single individual in the collec- 

 tion of the American Museum of Natural History, which I have referred to 

 this species with some doubt, there is preserved a small fragment of shell 

 which shows the exfoliated shell at least to have been finely but distinctly 

 radiated. It is possible, however, that it represents a distinct form, as it is 

 somewhat more transverse than any other one examined. Mr. Conrad's C. 

 curta is usually referred to the Miocene, but as the locality is very doubtful 

 the formation probably is also. 



Formation and locality. — In the lower layers of the Upper Marl Bed, at 

 Shark River, near New Egypt, and at Squankum, New Jersey. 



Crassatella DelaTTv-arensis. 

 Plate XXVII, Figs. 14 and 15. 



Crassatella Delawarensis Gabb. J. A. N. Sci., new ser., Vol. lY, p. 303, PI. XL VI, Fig. 



20 ( = 21 of text). Synopsis, p. 112. Meek, Checklist, p. 11. Geol. Surv. 



N. J., 1868, p. 726. 

 Etea Delawarensis (Gabb) Conrad. P. A. K Sci., Phil., 1876, p. 275. 



Shell below a medium size, cuneately-ovate or subtriangular in out- 

 line; beaks moderately elevated and situated considerably within the ante- 

 rior third of the entire length. Hinge-line rapidly dechning toward the 



