276 
PAL2E0NT0LOGY OF NEW YORK. 
This species is distinguished by its size, the moniliform siphuncle, and the 
distance between the septa. 
In its vertical distribution it is found in the upper beds of the Hamilton, and 
cannot be specifically distinguished from a form in the lower strata of the 
Chemung, noticed below as a variety. 
Formation and localities. From the Hamilton group, in various localities in 
Central New York. 
Orthoceras Bebryx, var. Cayuga, n. var. 
PLATES XXXIX, FIG. 1; LXXXVI, FIGS. 3-5; XCI, FIGS. 1-5; XCII, FIGS. 1-5. 
Orthoceras Bebryx, Hall. Illustrations of Devonian Fossils : Cephalopoda. Explanation of plate 39. 1S76. 
Numerous individuals have been observed among collections from the base of 
the Chemung group which appear to be specifically identical with this species 
as occurring in the Hamilton. The only difference noticed is the comparatively 
deeper air-chambers, which are about as three to four in the two forms, when 
& 
measurements are made at points on the tube having the same diameter in 
the different specimens. From the specimens included in this variety several 
additional features have been observed, not clearly shown in the individuals 
from the Hamilton group. The transverse section is circular. Chamber of 
habitation cylindrical, well developed, its full extent not being observed. Septa 
smooth and thin. Siphuncle excentric, distant from the dorsal and ventral 
margins in the ratio of 3 to 7, or twelve and twenty-eight mm., where the tube 
has a diameter of forty mm. 
A small individual, referred to this variety, embracing the greater portion of 
the chamber of habitation and nine of the adjacent air-chambers, has a length 
of 124 mm., and shows a broad, gentle constriction anterior to the middle of 
the grand chamber. A larger specimen, consisting of a portion of the chamber 
of habitation and nineteen air-chambers, has a length of 240 mm., of which 
75 mm. pertains to the chamber of habitation, which has a diameter of fifty- 
five mm. Large fragments of the grand chamber have been observed, having 
a diameter of seventy-five mm. 
