95 



Pygidium semi-oval, apparently about one-third the length of the head ; 

 the axis convex, acutely conical, and of five segments. Side-lobes flat, 

 with three obscure furrows, which do not reach the margin. The pygidium 

 seems to have a smooth border abruptly turned down all round, but this 

 remains doubtful. Surface smooth. About the middle of the glabella 

 there is a small rounded tubercle. 



Length of specimen, 5 lines. Width at posterior margin of head, about 

 4 lines. Length of head, 2J hues. Length of thorax. If lines. Length 

 of pygidium, about 1 line. 



In the specimen, the glabella and the whole of the left cheek are very 

 perfect. A fracture crosses the thorax, just behind the first segment, and 

 it is barely possible that in this place there was a segment which is not 

 preserved. My own impression is, that there are only six segments. The 

 axis is perfect, except at the fracture. The left side lobe is also perfect, 

 with the exception of the ends of the pleurse, where some obscurity exists. 

 The right cheek, the greater part of the right side of the thorax and py- 

 gidium, are not preserved. 



This species is dedicated to the excellent American palaeontologist, Mr. 

 F. B. Meek. 



Locality and Formation. — Point L^vis ; in the upper part of Umestone 

 No. 2, Quebec group. 



Collectors. — Sir W. B. Logan, J. Richardson. 



HOLOMETOPUS AnGBLINI. (N. Sp.) 



Fig. 85. 

 Fig. 85. — Holometopus Angelini. — a, Side view of head ; b, a nearly perfect head. 



Description. — Head semicircular, moderately convex, length about equal 

 to half the width. Glabella five-sixths of the length of the head, narrow, 

 and depressed cylindrical, with the sides parallel to the posterior half, then 

 gradually enlarging to twice the width at the front, which is broadly 

 rounded ; anterior angles of glabella rather obscure, but apparently acute- 

 ly rounded. The sides of the glabella are separated from the cheeks by 

 the deep dorsal furrows, which are obscurely angular at the bottom and 

 wide above ; they extend as far as the anterior angles, but do not run 

 round the front. Cheeks tumid; eyes small, apparently crescentiform, 

 situated about their own diameter from the posterior margin, and about the 



