290 PALjEONTOLOGT of NEW-YORK. 



CEPHALOPODA OF THE NIAGARA GROUP. 



The Cephalopoda of this group form no very conspicuous feature among its organic contents. 

 Notwithstanding the extensive excavations at Lockport, and the opportunities for examination 

 at Rochester and other places, the species obtained arc comparatively few, most of them rare, 

 and all usually in a bad state of preservation. This is in remarkable contrast with the strata of 

 the lower portion of the system, which everywhere contain remains of Orthocerata. 



The specimens obtained afford little opportunity of investigating their internal structure ; 

 and we are forced to depend upon tlie often obscure surface mark'ngs alone, for specific dis- 

 crimination. 



653. 1. GOMPHOCERAS'? 



Pl. LXI. Fig. 1 a, b. 



Subfusiform, aperture narrowed, gradually tapering to the extremity ; surface striated trans- 

 TCKcly. 



This fossil has the general form and appearance of Gomphoceras, though I am unable to 

 discover any marks of septa. The greatest expansion appears to be at about one third of the 

 distance from the aperture to the apex. 



Fig. 1 a. A young individual much compressed, in the shale. 

 Fig. 1 6. A larger individual from the limestone. 



Position and locality. In the shale at Rochester, and in a fragment of limestone below the 

 cliff at Niagara Falls. 



654. 8. CYRT0CERAS1 CANCELLATUM (n. 5p.). 



Pl. LXI. Fig. 2 a, b, c. 



Arcuate ; section tranversely oval ; surface transversely striated j shell tliin ; surface beneath 

 the shell showing faint longitudinal striae. 



The specimens figured are two fragments of the larger extremity of different individuals, one 

 of them being apparently the outer chamber only. 



Fig. 2 a. A fragment in shale, which is entirely compressed. The shell is retained on the larger 

 part of the surface, and, where exfoliated, the surface is marked by longitudinal striae. 

 Fig. 2 J. A fragment of a similarly marked specimen from limestone. 

 Fig. 2 c. Section of the same, showing the dorsal position of the siphuncle. 



Position and locality. The specimen fig. 2 a is from the shale at Lockport, and the other 

 is from a fragment of limestone below the cliff at Niagara Falls. 



