327 



Surface of the glabella and elevated cheeks apparently smooth. The 

 border is beautifully marked with radiating and irregularly branching 

 striae. This species differs from H. Ottawaensis (ante^ p. 182), in having 

 the glabella more elongate and parallel-sided and in having the border 

 striated instead of punctured. 



H. antiquatus of the Chazy limestone has the whole of the glabella 

 punctate, and seems to have a narrower border. 



Dedicated to Dr. J. A. GRANT, F.G.S., Ottawa. 



Locality aud Formation. Stanbridge, range 6, lot 20 ; Quebec group. 



Collector. -T. C. Weston. 



ILLJENUS SIMULATOK. (N. sp.) 



Fig. 315. 

 Fig. 315. Illcenus simulator, tf, part of the head ; 6, the pygidium. 



Description. Head very convex, broadly rounded in front, usually 

 uniformly arched from the posterior to the anterior margin ; sometimes 

 more abruptly bent downwards in the middle. The glabella is gently 

 convex, its width equal to about half the length of the head measured on 

 the curve. The dorsal furrows are strongly impressed, extending a little 

 more than one-third the length of the head, and usually with a sigmoid 

 curve. Eyes about one and a half lines in length ; about their own length 

 from the posterior margin, and a little more from the dorsal furrows. 



Pygidium rather strongly convex, flatened in the axial region ; anterior 

 angles obliquely truncated, the line formed by the truncation forming an 

 angle of about 45 with the longitudinal axis of the body. The length 

 of the straight side on the angle is about half the width of the side lobe. 

 The axis is gently convex and defined by the dorsal furrows for a little 

 more than one-third the length of the whole pygidium. The sides and 

 posterior margin are uniformly rounded. The length of the pygidium is 

 about two-thirds of the greatest width. 



The whole surface is covered with undulating fissure-like striae, from 

 three to five in one line. 



This species is certainly most closely allied to I. fraternus (ante, p. 



