4H CRETACEOUS .PALEONTOLOGY. 



anteriorly. On some individuals one or more of the ribs on the 

 posterior slope appear to be divided, while all are strongly ele- 

 vated and rather sharp with narrow interspaces. On the matrix 

 there are remains of distinct elevated concentric lines at regular 

 distances crossing the radiating ribs." (Whitfield.) 



The dimensions of a large internal cast of a right valve are : 

 length, 11.5 mm. ; height, 9.5 mm. ; length of hinge-line, 8.5 mm. ; 

 convexity, 4.5 mm. 



Remarks. This species generally occurs in the form of internal 

 casts, in which condition the umbo appears to be more promi- 

 nent than when the shell itself is preserved. The impressions of 

 the exterior show that the surface of the shell was covered with 

 strong, close, concentric lines in addition to the radiating mark- 

 ings, and in one of the largest individuals observed the number 

 of radiating costse is seen to be about 40. 



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

 wan (ioi 2 ), Lorillard (IO2 1 ), near Jamesburg (141), Lenola 

 (163); Woodbury clay, Lorillard (102), near Matawan (103). 

 Crosswicks (168), near Haddonfield (165, 183) ; Wenonah sand, 

 near Marlboro (I3O 1 ) ; Red Bank sand, near Middletown (112). 



Geographic distribution. New Jersey. 



Genus AXINSA Poli. 

 Axinea subaustralis (d'Orbigny). 

 Plate XXXV., Figs. 1-8. 



1834. Pectunculus australis Morton, Synop. Org. Rem. Cret. 



Gr. U. S., p. 64. (Not P. australis Quoy 1833.) 

 1850. Pectunculus subaustralis D'Orb., Prod, de Pal., vol. 2, p. 



243, No. 667. 

 1861. Axinaea subaustralis Gabb, Synop. Moll. Cret. Form., p. 



159 (103). 

 1 86 1. Axin&a, subaustralis Gabb, Proc. Acad. Nat. Sci. PhiL 



(1861), p. 365- 

 1864. Axincea subaustralis M'eek, Check List Inv. Foss N. A. r 



Cret. and Jur., p. 8. 

 1868. Axincea subaustralis Con., Cook's Geol. N. J., p. 725. 



