CEPHALOPODA OF THE CRETACEOUS MARLS. 245 
in the shell. Dorsum sharply rounded. Septa distant, rather deeply con- 
cave; arched forward on the margin of the umbilicus and slightly backward 
on the sides, but strongly arched forward on the dorsum. Siphon rather 
large, situated about two-fifths of the entire distance of the length of the 
septum from the inner border. Aperture as shown by the section of the 
volution, longer than wide and deeply emarginate on the inner border by 
the intrusion of the inner volution, giving it a compressed reniform outline. 
Surface of the shell unknown. 
The type specimens of this species, which are before me, consist of 
two fragments of casts, one consisting of about half of an inner volution 
preserving seven chamber fillings; and parts of four chambers of a much 
larger specimen show it to have been a rather large shell of a form much 
like the living Nautilus umbilicus, but with the umbilical cavity less angular 
on the margin and rounded within; the outer volutions embracing the inner 
ones to nearly the same extent. The sides of the volutions are not quite 
so much flattened near the umbilical region, giving a little greater propor- 
tional thickness to this part of the shell. It is so distinct from N. Dekayt of 
the Lower Green Marls that it is not necessary to compare it with that species. 
It is less unlike the forms of Nautilus found as casts at Prairie Bluff, Ala- 
bama, and in many parts of Texas known as N. perlatus Morton, but so far 
as I know those are not umbilicated, consequently it presents a radical differ- 
ence in this respect. There are some discrepancies between Mr. Gabb’s 
description and the specimens which it may be well to note. For instance, 
he states that the sides are flattened and ‘nearly parallel,” which I find to 
be very far from the case, especially in the larger specimen. He also states 
that the siphon is “small” and “central.” It is considerably nearer the 
inner margin than the center in both specimens, and in the larger one is fully 
three-sixteenths of an inch in diameter, being very much larger than in the 
living form of Nautilus. 
Formation and locality: In the yellow lime sands of the Middle Marl 
Beds at Vincentown, New Jersey, having been collected by the late Col. 
Bryan, and is now in the cabinet of the Phila. Acad. Nat. Sci. 
