202 



and cutting the front and posterior margins far outwards. The free 

 checks are not quite so smooth as the central lobe of the head, but no 

 radiation or other marking is visible. 



" Glabella bell-shaped ; -width, less than one- third of the entire head ; 

 broadly rounded in front, reaching nearly to the front margin ; depressed 

 convex at the neck lobe ; neck furrow Avell defined, extending across, and 

 directed obliquely forward at each side — two oblique glabellar furrows at 

 each side in front of the latter, making an angle, anteriorly, of about 45® 

 with the axis ; the furrows are -fvell marked interiorly, but very obscure 

 at the sides, and are separated by about one-half the width of the glabella, 

 forming three lateral lobes of nearly equal size, each larger than the neck 

 lobe. In some specimens there are three glabellar furrows on each side, 

 the front one making a greater angle, anteriorly with the axis, than either 

 of the others. 



" Pleurae twelve ; moderately convex outward from the axial furrow, 

 each marked by an equal deep groove to the tips, which are of a horny 

 aspect, recurved and extended into long spines ; sides parallel as far back 

 as the eighth segment, then gradually converging to the pygidium. 



" Axis convex, gradually tapering to the extremity of the tail, about 

 two-thirds of the Avidth of the pleurjB anteriorly — less at the pygidium ; 

 twelve body rings, and five or six caudal joints ; the body rings notched 

 above, posteriorly, and slightly swelled at the axial furrows. 



" Pygidium entire, semi-circular, truncate behind ; lateral lobes de- 

 pressed convex, on a level with the pleurse ; four broad ribs on each side 

 of the middle lobe, recurved towards the extremities ; margin smooth and 

 entire, anterior angles moderately rounded. 



" Dimensions of largest specimen : 



Entire length ...» 16 lines. 



Length of head 5 " 



' of thorax 8 " 



'« of axis of tail 3 " 



Width at base of head 11 " 



" at eighth segment 10 " 



" at front of pygidium 8 " 



" at axis at same place 1 J " 



Length of glabella 4 " 



Width at neck lobe 3J " 



" at front of glabella 2^ " 



" between the eyes 4 " 



" of margin in front of glabella OJ " 



" ofborder OJ « 



