310 I'ALJEOSTOLOGY OF NEW YORK. 



Septa smooth, thin, moderately concave. Sutures straight and horizontal. 



Siphuncle suhcentral, moniliform. 



Test not preserved. The internal cast shows some traces of a lamellose- 

 striate surface. 



Internal mould smooth, with the sutures slightly impressed. 



An individual, nearly entire, has a length of 107 mm., with a diameter of 

 twentv-five mm. near the aperture, and contains the chamber of habitation 

 and nineteen air-chambers. 



This species, in general proportions, resembles 0. cochleatum, and is distin- 

 guished by its smaller apical angle, somewhat deeper air-chambers, and its 

 straight and horizontal septal sutures. 



Formation and localities. From sandstones of the Chemung group, south of 

 Ithaca, N. Y., and at Warren, Pa. 



Orthoceras fulgidum, n. sp. 



PLATE XC, FIGS. 2, 3. 



Shell straight, slender, regularly enlarging to the aperture. Transverse section 

 subcircular. Apical angle 6°. Initial extremity unknown. 



Chamber of habitation small, regularly expanding with the general con- 

 tour of the tube, having a length of once and a half the diameter at the 

 last septum. Aperture slightly contracted, with the margin acute. Air- 

 chambers regular ; depth equal to three mm., and showing but little variation 

 in a length of twenty-five mm. 



Septa smooth, thin, with a concavity equal to the depth of the air- 

 chambers. Sutures straight and horizontal. 



Siphuncle small, suhcentral ; it? remaining characters have not been 

 observed. 



The test has a thickness of .5 mm. Surface marked by fine, rounded 

 stria? of growth. Internal mould smooth. 



A fragment, preserving the chamber of habitation nearly entire and twelve 

 air-chambers, has a length of forty-five mm., with a diameter of six and ten 

 mm., respectively, at the two extremities. 



