OROMETOPUS ELATIFRONS. 47 



wards across the cheeks to the eyes, whose distance apart is half the distance 

 between the ends of the fixed cheeks. From the same points at the sides of the 

 glabella broad, shallow furrows run obliquely backwards, cutting off triangular 

 areas which rise towards the neck-segment into prominent elevations on either 

 side. Palpebral lobes fairly elevated. Eyes small, about sixteen facets only being 

 seen in a rather small but adult individual. Anterior part of the facial suture 

 bowed outwards, cutting the raised rim in front of the eye, continuous with its 

 fellow of the other side as a gentle curve on the bevelled front of the shield ; 

 posterior part running outwards and cutting the posterior margin after circum- 

 scribing the ends of the fixed cheeks. 



" Thorax of eight segments, 1 broad and short, narrowing behind, the lateral 

 margins forming part of a circle. Axis prominent, one quarter the width of the 

 whole thorax. Segments short; axial parts forming prominent, rounded, back- 

 wardly bowing rings ; pleurae straight, long, hollowed almost symmetrically, their 

 ends in the first segments more pointed, in the hinder segments abruptly bent 

 downwards and truncated. 



" Tail short, triangular, margin bent downwards. Axis broad, extending to 

 the edge of the upper surface, of four distinct segments. On the limb only the 

 first segment is clearly indicated. 



" Associated on the same slab (R. R. 2294) with three individuals of 

 Orometopus is a doublure of corresponding size with hypostome attached, which 

 almost certainly belongs to this species. The doublure is convex, moderately 

 broad, and has no suture across it (unless along the median line). It is orna- 

 mented with longitudinal raised lines, of which there is a second set regularly 

 intercalated in front. Attached to one side of it is a fragment of the impression 

 of the skin of the cheek regularly ornamented. The hypostome is transversely 

 oblong or oval and, except for the curved anterior margin, which extends as small 

 wings beyond the sides, is polygonal, of sub-equal sides, its posterior margin 

 being made of three and its lateral margins of one each. Its greater part consists 

 of a transversely oval convexity bordered by a shallow furrow deepening into 

 two hollows at the sides. Outside this furrow, except at the extreme ' front, is a 

 narrow, slightly convex rim. The surface is ornamented by fine raised lines. 



" Dimensions of the specimen (R, R. 2294), Plate IV, fig. 8 : 



Total. Cranidium. Thorax. Tail. 



Length . . 5-1 . 2-2 . 2-3 . 075 mm. 



Breadth 5*8 5-4 . 4*4 . 2- 7 mm. 



The specimen lacks the free cheeks and tail, which are calculated from material 



kindly lent by Mr. E. S. Cobbold. The total breadth is measured to the edges 



1 " In the Survey specimen E. E. 2294 there are eight segments. In Mr. Cobbold's specimen 

 also there are eight; but the head being separated from the trunk by a space, it is just possible that 

 there may have been nine in that specimen." 



