236 
PALAEONTOLOGY OF NEW YORK. 
septum, and its walls are apparently nearly uniform and straight in its 
passage through the air-chambers. 
The test, inferring from the crystalline matter remaining on some parts 
of the surface, has had a thickness of about two mm. Surface marked by 
irregular, lameilose striae. Internal cast smooth, with the exception of the 
constriction of the outer chamber, before noticed, and without special eleva¬ 
tion or depression of the interseptal spaces. 
This species differs from 0. Pelops, which it closely resembles, in the more 
gradual expansion of the tube towards the aperture, and in the greater 
proportional distance of the septa, which are about as five to seven, and also 
in their greater concavity. In the gradual expansion of the tube, and distance 
of the septa, it approaches some of the forms in the higher rocks, from which 
it is otherwise very distinct. See 0. Eriense, plate 40, of the Hamilton group? 
and 0. Atreus, of the Portage group. 
Formation and locality. This species occurs in the upper beds of the Scho¬ 
harie grit, near Clarksville, Albany county, N. Y. 
Orthoceras Oiiioense. 
PLATES XXXV A, FIGS. 8, 9 ; XXXVI, FIG. 4. 
Orthoceras Pelops, v&r. OMoense, Hall. Illustrations of Devonian Fossils: Cephalopoda, pi. 36, fig. 1. 1876 
Shell slightly curved—curvature exogastric. Transverse section circular. 
Cone regularly and gradually enlarging. Apical angle about 9°. Initial 
extremity unknown. 
Chamber of habitation large, the portion preserved in an imperfect 
specimen being about twice as long as its diameter at the base. Aperture 
unknown, apparently slightly contracted. 
Septa thin, obliquely curved with regard to the axis of the shell, the mar¬ 
gins being advanced further forward on the concave or dorsal side of the 
shell; in the smaller part of the shell (in the specimen figured), distant about 
one-sixth, and in the larger portion, near the outer chamber, about one- 
seventh of the diameter, varying in actual measurement from five to seven 
