CEPHALOPODA. 327 



GOMPHOCERAS RUDE, n. Sp. 

 PLATE XCIIt, FIG. I. 



Shell gibbous, curved ; curvature exogastric. Point of greatest transverse 

 section near the last septum. 



Chamber of habitation large, having a length greater than the diameter of 

 the tube at the last septum. Crenulated band cancellated by five imbricating, 

 lamellose striae, crossed by numerous small furrows. The width of the zone 

 is about ten mm., and there are six furrows in the space of seven mm. 



Aperture, septa and surface-markings unknown. 



Air-chambers deep, shallower near the chamber of habitation ; varying in 

 depth from twelve to six mm., in the length of three chambers over the 

 ventrum. The air-chambers are considerably shallower on the dorsal side, 

 owing to the curvature of the tube. Sutures horizontal, making a slight 

 sinus, which is convex toward the aperture, over the siphuncle. 



Siphuncle near the ventral side exposed in the process of weathering ; but 

 its elements have not been fully observed. 



The specimen figured has a length of ninety-five mm., about half of which 

 belongs to the chamber of habitation, — five air-chambers occupying nearly 

 fifty mm. of the length. 



This species is distinguished by the character of the crenulations and the 

 great depth of the air-chambers. The specimen described is much compressed 

 and distorted, and imperfectly preserved, but the characters above indicated 

 are very marked. 



Formation and locality. In the Schoharie grit, at Schoharie, N. Y. 



