CRUSTACEA. 197 



Distribution. This species is represented in the collection of the State 

 Museum by fifteen specimens, most of which are in a very fragmentary condi- 

 tion, on account of the fragility of the test. In one locality, at the lower falls 

 of Vinegar Brook Glen, near Norton's Landing, on Cayuga Lake, individuals 

 have proven to be quite abundant in the shales, but arc so massed together and 

 macerated as to be unsatisfactory for purposes of description. Hamilton group. 

 In the shales at Tichenor's (Hen, Canandaigua Lake; near Norton's handing, 

 Cayuga Lake, and upon the shores of Owasco Lake. 



Rhinocaris scaphopteka, n. sp. 



PLATE XXXI, KIGS. ii, 23. 



Cephalothorax elongate, outline as in Tropidocaris. The prora at the anterior 

 extremity is shorter than in the foregoing species, is vertically flattened and 

 narrowly lanceolate, slightly broadened on its upper edge toward the base. 

 The margin curves rapidly backward from the base of the prora to the ven- 

 tral edge, thence slightly upward to the posterior margin, which is transverse 

 and somewhat incurved over the dorsum. The single specimen of this species 

 which has been observed, is folded unsymetrically along the dorsum, and is 

 laterally compressed. There are indications of a faint ridge in the axial 

 line of the carapace, but this part has been broken along one side of that line. 

 A strong lateral carina beginning near the anterior extremity is nearly paral- 

 lel to the ventral margin, and becomes obsolete in the posterior region. Just 

 above its anterior extremity on each side is a low elevation, which is prob- 

 ably an optic node. 



The Surface is ornamented, on the lateral regions below the carina, with 

 elevated lines parallel to the ventral margin, which are stronger and more 

 frequently interrupted than in Rhinocaris columbina. The surface of the 

 median area within the carina?, bears elongate linear nodes parallel to the 

 axis, and several of these are visible over the surface of the optic spot. The 

 intermediate space between the lines and nodes is minutely punctate. The 



