407 



in the posterior third ; sides gently convex, nearly straight, sub-parallel, 

 slightly more distant from each other towards the front than behind, front 

 obtusely rounded. The neck segment and furrow are rounded and well 

 defined all across ; the posterior glabellar furrows are rather strong, 

 directed forwards at an angle somewhat less than 45°, their inner extre- 

 mities separated by one-third the width of the glabella, and distant from 

 the neck furrow about the width of the neck segment. In front of these 

 are two obscure, nearly vertical furrows on each side, at about equal dis- 

 tances from each other. The fixed cheeks are strongly elevated, and 

 separated from the glabella by the deep, narrow dorsal furrows. The eyes 

 are small, £lnd situated on a line drawn across the head, passing about 

 midway between the two posterior glabellar furrows. They are connected 

 with the front lobes of the glabella, by slender ocular ridges, as in the 

 genus Oonocephalites. The distance of the eye from the glabella is a 

 little more than half the width of the neck segment. The facial suture 

 cuts the front margin, a httle inside of a line drawn through the eye, 

 parallel with the length of the body. Behind the eye it runs obliquely 

 outward with a gentle curve, and cuts the posterior margin at a point 

 between the line passing through the eye, and the posterior angles of the 

 head. The surface in the large specimens is finely tubercular, but in the 

 small ones apparently smooth. Length of largest head seen five fines and 

 a half ; the width of the glabella at one-third the length from the front, 

 is about three-fourths of its own length, excluding the neck segment and 

 furrow. Moveable cheeks, thorax and pygidium unknown. 

 Limestone, No. 1. 



•') 



Mbnocephalus Sedgwicki. (ISr. sp.) 



Fig. 387. Fig. .^88. 



Fig. 387. — Menocephalus Sedgwicki. 



388. — M. globosus. a, side view of the head ; b, upper side ; c, front view. 



Description. — Glabella very convex, conical gradually tapering from 

 the neck segment to the front, which is obtusely rounded. Neck segment 

 and neck furrow well defined all across. Two glabellar furrows on each 

 side, which divide the glabella into three pair of lobes, the anterior pairs a 

 little the largest, the other two nearly equal to each other. The posterior 

 furrows sometimes curve so far backwards as to isolate the lobes from the 

 body of the glabella ; their depth, however, is inconsiderable. The gla- 



