ORTHOCERATID-E. 
99 
a diameter equal to, or two-thirds the depth of, the air-chambers. 
The septa are usually macerated, or broken from compression, and 
the position of the siphuncle has not been satisfactorily determined. 
One small fragment, referred to this species with doubt, retains the 
septa, and shows the siphon in a slightly eccentric position. 
“ The test has not been preserved. The casts of the interior indi- 
cate a transversely lamellose-striate surface This species is 
distinguished by its size, the moniliform siphuncle, and the distance 
between the septa . . . .” 
The above is Prof. J. HalTs description of Orthoceras Bebryx, 
which occurs in the Hamilton Group, “ in various localities in 
Central Xew York.” 
The variety Cayuga, which has been observed in the lower mem- 
bers of the Chemung Group, is said to differ from the species only 
in “ 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 miUimetres, where the tube has a 
diameter of forty millimetres. . . . 
“ The specimens embraced in this variety and in the species above 
constituted are all very imperfect.” 
Horizon. Chemung Group, Upper Devonian. 
Locality. Ithaca, State of New York. 
Represented by one imperfect specimen, presented by J. £. Lee, 
Esq., F.S.A., F.G.S. 
Orthoceras, sp. 
Remarks. These specimens are not in a condition for specific 
identification. They consist of three or four fragmentary casts 
much distorted, crushed, and weathered. The matrix is a sand- 
stone. Two of the specimens exhibit the septa, which have a con- 
siderable obliquity, and are highly arched. The siphuncle appears 
to have been eccentric. The rate of tapering cannot be accurately 
made out, but it was rather slow. 
I have consulted Messrs. Sharpe and Salter’s Memoir on the 
Devonian Fossils of the Cape Colony (Trans. Geol. Soc. 2nd series, 
H 2 
