263 



inwards on approaching the margin, behind the eye running outwards sub- 

 parallel to the neck furrow, and cutting the margin before reaching the 

 outer angle. Thorax distinctly tri-lobed, about nine segments ; pygidium 

 with the axis usually short and not strongly grooved ; side lobes, with 

 short ribs sometimes indistinctly developed ; a broad smooth border aU 

 round, which is sometimes concave. 



This genus should perhaps be regarded as a sub-genus of Bathyurus. 

 The typical species of this latter, such as B. extans, B. Nero, and B. 

 Cylele, have a sub-cylindrical glabella rounded in front, strongly convex, 

 and with obscure glabellar furrows. In this genus the glabella is conical 

 or pointed in front, and exhibits no trace of furrows. The pygidium also 

 differs in not being strongly convex, in having a shorter axis, and in 

 general a wider border. 



In Newfoundland we first find this genus in Division F, in rocks which 

 appear to be of the age of the lower part of the Calciferous formation, and 

 it ranges upwards to Division P, through a thickness of more than 3000 

 feet. It occurs in Newfoundland, near Quebec, and at Phillipsburgh. 

 At Swanton, in Vermont, a species has been found in the Trenton, which 

 may belong to this genus. 



Bathyurbllxjs abruptus. (N. sp.) 



Fig. 2i1. Fig. 248. Fig. 249. Fig. 250. 



Fig. 247. — Eathyurellus abruptus. The glabella and fixed cheeks. 



248. — B. marginatus. The glabella and part of the fixed cheeks; 



249. — Supposed pygidium of B. marginatus. 



260. — Pygidium most common, with B. abruptus, enlarged two diameters. 



Description. — Glabella cylindro-conical, sides parallel, front rather 

 narrowly rounded and scarcely at all elevated or defined from the smooth 

 anterior margin. Neck furrow nanow, extending all across. Neck 

 segment rather broad, and depressed convex. Judging from the form of 

 the palpebral lobe the eye is large and semi-annular, and a little more 

 than one-half the length of the glabella, the posterior angle close to the 

 neck furrow, and the anterior angle almost in contact with the side of the 

 glabella a little in advance of the mid-length. Around the front of the 

 head there is a smooth border which is somewhat concave, and varies in 



