PAL2E0NT0L0QY OF NEW YORK. 

 Cvrtoceras Hector, n. sp. 



PLATK XC, FIGS. 11-15. 



Shbll apparently nearly straight, regularly enlarging to the aperture. Trans- 

 verse section broadly oval. Apical angle about 14°. 



Chamber of habitation small, having a length equal to the dorso-ventral 

 diameter of the tube at the base. Sides expanding regularly with the gen- 

 eral contour of the tube, and contracting slightly at the aperture. 



Air-chambers regular, having a depth of about five mm. One specimen 

 shows several very shallow air-chambers near the grand chamber. 



Septa smooth and thin, moderately concave. Sutures considerably curved 

 and oblique. 



Surface marked by fine striae of growth, with a few coarser, lamellose lines 

 at the margin of the aperture. 



One fragment, showing the extent of the grand chamber, and embracing 

 seven air-chambers, has a length of forty-three mm., of which twenty-five 

 mm. pertain to the outer chamber. Another fragment shows eight air-cham- 

 bers in the length of thirty-three mm. 



This species is distinguished from C. densum of the Hamilton group by its 

 smaller size and curving septal sutures. 



Formation and localities. In the sandstones of the Upper Chemung, south of 

 Olean, N. Y., and in the same horizon at Warren, Pa. 



Cyrtoceras liratum. 



PLATK XC'V, FIG. 1. 



Aplocera* (Cyrtoceras) liratum. Hall. Descriptions of New Species of Fossils, etc., p. 44. 1861. 



Fifteenth Rep. N. Y. State Cab. Nat. Hist., p. 72. 1862. 



Shell arcuate, regularly and rapidly enlarging. Transverse section circular. 

 Apical angle about 28°. 



A portion of the chamber of habitation has been observed, possessing no 

 marked characters. Air-chambers regular, having a depth of four mm. 

 Sutures straight and horizontal. 



