GA-STEROPODA OI* THE LOWER GREEN MARLS. 158 



Modulus, as being more probably its true position than elsewhere. Although 

 the surface characters of the shell are really unknown, there are slight evi- 

 dences on one of them of the shell having been thin, with a transverse 

 lamellose structure within and near the umbilicus. There are also faint 

 indications of a few distant subangular spiral ridges on and below the 

 periphery of the outer volution of the best cast. 



This shell has been usually identified with Belphinula lapidosa Morton, 

 the type of which was from Alabama, and is figured on the plate with this 

 one for comparison. It will be seen from that, that the difi^erence in form 

 of the cast, the size and character of the umbiliciis, and want of tooth, 

 entirely separate them generically. 



Formation and locality: The specimens are from the collection Acad. 

 Nat. Sci., Phila., and are marked as "Cretaceous, N. J.," only. They, how- 

 ever, are evidently from the Lower Marl bed, and from their lithological 

 character I should say' three of them were from the brown layers near Bur- 

 lington, and the other, the figured example, from near MuUica Hill, New 

 Jersey. 



Order SCUTIBRANCHIATA. 

 Suborder EDRIOFHTHALMA. 



PATELLID^. 



Genus HELCION Montfort. 



HELCION ? TENTORIUM. 



Plate XIX, Figs. 6-8. 



Patella tentorium Morton : Synop. Org. Rem. Cret., p. 50, PI. i. Fig. 11. 



Helcion tentorium (Mort.) D'Orb., Prod, de Pal^ont., vol. 3, p. 332; Gabb, Syn- 

 opsis, p. 57 ; Meek, Check List Cret. and Jur. Foss. , p. 17. 



Hipponyx tentorium, Morton: Jour. Acad. Nat. Sci., Phila., 1st ser.,vol. 8, p. 

 210. 



Halcyon ? tentorium (Mort.) Meek : Geol. N. J., Newark, 1868, p. 738. 



Shell small, orbicular or subcircular in outline, being slightly longer 

 than wide, and measuring about half an inch in length; very depressed 



