472 CRETACEOUS PALEONTOLOGY. 



radiating markings are the conspicuous feature of the shell and 

 can be detected upon the casts as preserved in New Jersey, as well 

 as upon the shells themselves or the impressions of the exterior. 

 The nearly flat right valve and the nearly equal size of the auricu- 

 lations are other characters distinguishing burlingtonensis. This 

 species is also never so high and narrow proportionally as argil- 

 lensis, although some members of the latter species sometimes 

 have nearly the same proportions as specimens of burlingtonensis. 

 The two species occur together in both the Merchantville and the 

 Woodbury formations, but burlingtonensis is more common in 

 the Merchantville, while argillensis is the commoner species in 

 the Woodbury, but wherever they occur there is not the least 

 difficulty in separating them. Gabb's type specimen was from the 

 Merchantville. Whitfield's figure 7 seems to be a member of 

 this species with one ear injured, but its identity cannot be de- 

 termined from the figure alone. Pecten perlamellosus Whit, 

 is apparently only an immature example of P. burlingtonensis, 

 these young individuals being closely similar to P. conradi ex- 

 cept that the concentric bands are somewhat broader and con- 

 tinue in nearly full strength across the auriculations. 



Formation and locality. Merchantville clay-marl, near Mat- 

 awan (101), near Jamesburg (141), Lenola (163), Burlington 

 (Gabb) ; Woodbury clay, Lorillard (102), near Haddonfield 

 (183) ; Wenonah sand, near Marlboro (130). 



Geographic distribution. New Jersey. 



Pecten argillensis Conrad. 

 Plate XLIX, Figs. 1-4. 



1860. Pecten argillensis Con., Jour. Acad. Nat. Sci. Phil., 2nd 



ser., vol. 4, p. 283. 



1 86 1. Pecten argillensis Gabb, Synop. Moll. Cret. Form., p. 



213 (i57). 

 1864. Pecten argillensis Meek, Check List Inv. Foss. N. A., 



Cret. and Jur., p. 7. 

 1869. Camptonectes bellisculptus Con., Am. Jour. Conch., vol. 



5, P- 99, pl- 9, fig- ii. 



