30 
PALEONTOLOGY OF NEW YORK. 
depth, where the tube measures 28 mm. in greatest diameter. But little 
variation in the depth of the air-chambers can be noticed in the tube for a 
length of 125 mm. 
Septa thin, deeply concave. Sutures somewhat curved, not deeply im¬ 
pressed on the internal mould. 
Siphuncle moniliform, excentric, distant more than one-third the diameter 
of the tube from the ventral side. 
Test marked by irregular lamellose lines of growth, which make a distinct 
retral curve on the ventral side of the tube. 
Internal mould smooth. The apical portions of the shell show an organic 
deposit partially filling the air-chambers; but on account of the preservation 
of the specimens in a sandstone, its minute characters cannot be described. 
The specimen illustrated, has a length of 185 mm., with a diameter of 38 
mm. near the aperture and 9 mm. at the distal extremity. 
Individuals of this species are of frequent occurrence in a sandstone at 
Panama, N. Y., and are better preserved than is usual with other forms of this 
class from similar deposits in the Chemung group. The species may be dis¬ 
tinguished by the rapid enlargement of the tube, the oval transverse section and 
the position and form of the siphuncle. 
Distribution. In a sandstone of the Chemung group, at Panama, Chautauqua 
county. 
Orthoceras Indianense. 
PLATE CXVIII, FIGS. 6-10. 
Orthoceras Indianensis, Hall. Thirteenth Ann. Kept. N. Y. State Cab. Nat. Hist., p. 107. 1860. 
Ortkoeei-as Bcedahis, Hall. Fifth Ann. Kept. State Geologist. Expl. pi. (IIS) 2, figs. 6-11. 1886. 
Shell small, straight, slender; transverse section circular. Apical angle six 
degrees. Initial extremity unknown. 
Chamber of habitation long, gradually enlarging from the last septum for 
two-thirds its length, and then contracted by a broad constriction, from which 
the tube enlarges to the aperture. Air-chambers regular, very gradually 
increasing in depth to the last septum, six in the length of 22 mm. where 
the tube measures respectively 9 and 12 mm. in diameter. 
