74 SIXTEENTH REPORT ON THE CABINET OF NAT. HISTORY. 



CERATIOCAEIS ? PUNCTATUS ( n. s.). 



PLATE I. FIG. 8. 



The half of a carapace, having the aspect of one valve of a 

 monstrous Leperditia. The form is ovate, broader and rounder at 

 the posterior end, and without any apparent articulating face for 

 the abdominal joints, Surface strongly and deeply punctured or 

 pitted, with an aspect like shagreen. A strong node-like process 

 exists on the dorsal margin : and towards the anterior end are 

 two large low prominences, with two less elevated ones in front 

 of these, beyond which the surface is irregular, 



This fragment is referred with hesitation to the Genus Ceratiocaris, 

 both on account of its nodose surface, which has not been observed in any 

 of the other species, and chiefly from the peculiar punctured or granulose- 

 punctate texture of the crust. 



At the present time, no other specimens pertaining to this species are 

 known. 



From the collections made by Dr. C. A. Whiti; on the east shore of 

 Cayuga lake. 



Comparing the typical forms of the genus as given by Professor 

 M'CoY, and those already known from our Upper Silurian rocks, 

 there may be some doubt whether any of these here noticed 

 are true Ceratiocaris. With the meagre materials before me, I 

 have not thought it desira'ble to propose Siwy separation from that 

 genus at the present time, particularly since there is a generic 

 designation already proposed by Mr. Salter for an imperfectly 

 known Devonian form. When the Genus Dictyoc^ris shall be fully 

 known and described, we may be able to determine whether some 

 of these fragments pertain to that genus. 



GENUS DITHYROCARIS ( Scouler). 



The fossil remains which I have referred to this genus consist, 

 as before remarked, of the tripartite caudal appendages ; and at 

 this time, no other remains referable to this genus are known in 

 any of the Ne\Y-York strata. 



