422 
PALAEONTOLOGY OF NEW YORE. 
Formation and localities. The specimens of this form have been princi¬ 
pally obtained from the Marcellas shale, at Richmondville, Schoharie county. 
Some fragments of the same have been found at another locality in the same 
county. 
Nautilus magister, n. sp. 
PLATES LXII, CVII, FIGS. 1, 6, 7, 8; CVIII, FIGS. 1, 2. 
Nautilus Barrandi, Hall. Illustrations of Devonian Fossils: Cephalopoda, pi 62, fig-. 1; pi. 63, fig-. 1 ; 
pi. 64 A, fig. 2. 1876. 
Not N: Barrandei, von Hauer. Haidinger: Naturwissenschaftliche Abhandlungen, 3. Band, pi. 1. 1S50. 
Shell large, globose, the transverse and ventro-dorsal diameters being about as 
eleven to twelve, making about three volutions. Volutions re-entrant, 
embracing to one-tliird the diameter of the inner contiguous volution. 
Umbilicus comparatively narrow and profound. Transverse section elliptical, 
with a broad rounded sinus on the concave dorsal side. Transverse diameter 
the longer,—the two diameters being in the ratio of three to four. Tube 
rapidly enlarging. Apical angle about 18°. 
Chamber of habitation large, very ventricose, its capacity greater than 
the entire septate portion of the shell. The length, as compared with the 
greatest diameter at the base, is about as nine to seven, and somewhat rap¬ 
idly expanding to the aperture. Aperture-opening at right angles to the 
axis of the tube, with a gentle sinus in the centre of the convex ventral 
side. Air-chambers regular, and gradually enlarging toward the chamber 
of habitation, the last one being shallower than the preceding; having a 
depth of from eighteen to thirty mm. in the distance of eleven chambers, 
as exposed on the ventral side of the outer volution. 
Septa thin, regular, very concave ; concavity greater than the depth of the 
air-chambers; from three to four in the space of seventy-five mm., measured 
on the convex side of the outer volution of the shell, the distance on the 
umbilical margin being from seven to nine or ten mm. in the distance of 
eight septa. The margins are extremely advanced and highly imbricate on 
the ventral side. Their convexity in the transverse diameter is equal to 
106°, and in the direction of the ventro-dorsal diameter 110°. Some speci- 
