:;.. 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 CXVIU, FIGS. 6-10. 



< hi Inn eras /iiiHiiiu.iisis, Hall. Thirteenth Ann. Rept. N. Y. State Cab. Nat. Hist., p. 107. 1S60. 

 Orthoceras Dcedalus, Hall. Fifth Ann. Rept. State Geologist. Expl. pi. (118) 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. 



