420 
PALAEONTOLOGY OF NEW YORK. 
This species is closely allied to N. oriens , which presents a somewhat different 
surface-marking, with a closer coiling of the volutions, giving the appearance 
as if partially embraced by the outer volution. All the forms which have been 
referred to that species are laterally compressed, which may cause or augment 
this appearance. 
The N. maximus differs from N. magister in the more circular transverse sec¬ 
tion, in the less closely coiled volutions, and in.the surface-markings, as well as 
in the position of the siphuncle. 
Formation and localities. In the lower, arenaceous shales of the Hamilton 
group, at Earlville, Solsville and other places in Madison county; and in the 
higher shales of the group, near Borodino, on Skaneateles lake. 
Nautilus oriens. 
PLATES LXI; CV, FIG. 2; CVI, FIG. 8. 
Nautilus oriens , Hall. Illustrations of Devonian Fossils : Cephalopoda, pi. 61, fig'. 1. 1876. 
Compare Nautilus maximus (Cour.), Hall. Page 418, plates LXIII and LXIV. 
Shell large, subovoid, discoid, making about three volutions, which are slightly 
re-entrant. Umbilicus very wide, exposing all the volutions. Transverse 
section subcircular. Tube somewhat gradually enlarging in the inner volu¬ 
tions. The apical angle, as taken from a compressed specimen, is about 15°. 
Chamber of habitation large, ventricose, rapidly expanding. Aperture 
opening at right angles to the axis of the tube, with a gentle sinus on each 
side of the convex ventral face of the shell. Air-chambers regular, deep, 
increasing in depth with the enlargement of the volutions. The measure¬ 
ment of two specimens give a depth of twenty to twenty-five mm. 
Septa regular, distant, having a greater concavity than the depth of the 
air-chambers, strongly imbricating. As measured on the ventrum of one 
specimen, they have a distance of twenty-five mm., where the tube has a 
diameter of seventy-five mm. Suture lines strongly marked on the casts 
and partial casts of the interior. 
Test imperfectly preserved, and its thickness not determined. In the 
compressed and macerated specimens, partially retaining the shell, or its 
