14 



thorax is not sufficiently well preserved to enable me to describe it in 



detail. 



The following are the measurements of two of the specimens : Length 

 of head 4J lines ; length of glabella 3 lines, width, just in advance of neck 

 furrow, 2J- lines, and at one-third the length from front margin 2 lines. 



In a specimen consisting of the thorax and pygidium the whole length 

 is six lines, of which the pygidium occupies apparently a little less than 

 one line. Width at first segment 5J lines ; width of axis at same place 

 1 line ; width at anterior margin of pygidium about 3 lines. 



The position of the eye is not shewn in any specimen that I have seen, 

 but from the width of the portions of the fixed cheeks which remain, it 

 must be distant from the dorsal furrows nearly the width of the glabella. 



This species appears to be closely allied to the one above cited from 

 Shumard's paper, so far as the characters of the glabella are concerned. 

 As however the proportions are a little different, I shall dispose of it as 

 above until I can have an opportunity of submitting a specimen to Dr. 

 Shumard. 



Locality and Formation. 1J mile east of Swanton in Vermont, in the 

 slates of the Potsdam group. 



Collectors. Rev. J. B. Perry, Dr. G. M. Hall, and Sir W. E. Logan. 



CONOCEPHALITES VULCANUS. (N. Sp.) 

 Fig. 17. 



Description. Head broad, moderately convex; glabella obtusely 

 conical, with the neck segment triangular and extended backwards in the 

 middle ; neck furrow not extending across, being interrupted by a strong 

 carina which runs along the median line ; dorsal furrow all round, but 

 not sharply defined. Front margin about one-third the length of whole 

 head with a projecting rim, and a transverse groove situated two-thirds 

 the distance from the front of glabella. Cheeks moderately convex ; 

 ocular ridge well defined ; a line drawn across the head a little in advance 

 of the mid-length of the glabella, would pass through the eyes; the latter 

 distant from the glabella at least half the whole length of the head. No 

 indications of glabellar furrows visible. 



Length of head, 4J lines ; of glabella, including the backward project- 

 ing angle of the neck segment, 3 lines ; width of glabella just in advance 

 of neck furrow, 2J lines ; distance of eye from glabella, 2| lines. 



This species differs from 0. Adamsi, in the character of the neck 

 furrows, and in the greater proportional width of the glabella. 



It was found along with 0. Adamsi in the same beds. 



