258 PALEONTOLOGY OF NEW YORK. 



smaller extremity is eight mm., and the chamber of habitation has a diameter 

 of twenty-three mm. 



This species, of which only one specimen has been observed, is distinguished 

 from 0. procerus by its large apical angle, the concavity of the septa, and the 

 greater excentricity of the siphuncle. 



Formation and locality. The Schoharie grit at Schoharie, N. Y. 



Orthoceras carnosum, n. sp. 



PLATE XXXV, FIG. 11. 



Shell small, straight, regularly enlarging to a point near the middle of the 

 chamber of habitation. Transverse section broadly elliptical. Apical angle 

 about 9°. Apex unknown. 



Chamber of habitation short, somewhat gibbous ; point of greatest trans- 

 verse section near the middle, whence the shell contracts slightly, and 

 again expands before reaching the aperture, forming a shallow constric- 

 tion. Air-chambers regular, having a depth of from two to three mm., and 

 less near the base of the chamber of habitation. 



Septa smooth, having a concavity equal to an arc of 109°. Sutures straight 

 and horizontal. 



Siphuncle subcentral, large, having a diameter of two mm. where the 

 diameter of the tube measures ten mm. The elements have not been 

 observed in its passage through the chambers. 



Test thin, rarely preserved. Surface marked by fine, regular, lamellose, 

 transverse, arching strife, six in the space of two mm., crossed by finer, 

 longitudinal, cancellating striae. The striae are curved, forming a broad, 

 distinct sinus over the ventral side. 



The internal mould is essentially smooth, with the chamber walls flat, and 

 the sutures but little impressed. 



The only individual yet observed, which is referred to this species, has a 

 length of fifty-eight mm., including the outer chamber, with ten of the 

 attached air-chambers. 



