12 [361] A. Winchell on supposed New Cephalopods. 
which gives 3J to one-tenth of an inch; depth of lateral sinus 
•08 (5). 
Localities. Marshall and Battle Creek. 
Nautilus subsulcatus (?) 
Phillips (Geoi. Yorks., ii, 233, pi. xvii, 18, 25). 
The general outline of the transverse section is hexagonal, 
with well rounded angles. The sides are nearly plane, and par¬ 
allel with the dorso-ventral diameter, and in the ventro-lateral 
region slope abruptly into the umbilical cavity, making an angle 
with the side, of about 65°. The lateral surface joins the dorsal 
at an angle varying from 74° to nearly 90°. At a little less 
(apparently) than half the transverse diameter of the cast, the 
dorsum shows a small rectangular carina, similar to the one rep¬ 
resented by de Koninck in pi. xlix, fig. 4 b . The nature of the 
surface between this carina and the corresponding one on the 
opposite side of the peripheral line, has not been ascertained. 
The septa make a broad sinus coextensive with the lateral sur¬ 
face, and curve backwards again upon the dorsum. The angle 
of intersection with the sides shows that they are deeply con¬ 
cave. The inner whorl is somewhat impressed into the outer. 
External surface of cast is faintly marked by raised striae cross¬ 
ing in lines parallel with the septa; and on the umbilical slope 
are seen traces of coarser longitudinal striae. 
Greatest dorso-ventral dimension *8; width of lateral surface 
*6; width of dorsal surface to carina *27; width of ventral sur¬ 
face to impression of next inner whorl *38; interseptal space on 
the dorso-lateral angle *33distance of transverse striae *02, giv¬ 
ing 5 in one-tenth of an inch; distance of longitudinal striae *04, 
giving 2$ in one-tenth of an inch. A fragment of a larger 
specimen (wholly septate) must have belonged to an individual 
more than 4 inches across the outer whorl. In this, the lateral 
surface is *8, and the umbilical slope f 47. 
Locality. Marshall. 
The transverse section of these forms is much less sharply 
angular than is shown by the figures of European authors, and 
the striae seem to be coarser. 
Nautilus ingentior, n. sp. 
Shell very large; whorls not impressed; transverse section 
an ellipse whose larger diameter corresponds to the height of the 
shell, the sides in some specimens being somewhat flattened. 
Surface (of cast) smooth; septa bent abruptly forward at their 
junction with the shell so as to meet it at an acute angle, slightly 
sinuous,—a broad shallow sinus occupying the superior lateral 
portion of the surface; dorsum not seen. 
One fragment in my possession 3J inches long, one-half sep- 
