F. R. Coiqyer Reed — Utidescribed Trilohites. 9 



<1ouble its axial width, and with a squavely truncated extremity, 

 not projecting beyond the margin. A straight diagonal furrow 

 marks the surface, but does not reach the extremity, and the outer 

 anterior angle of the truncated end is flattened as in the pleurte of 

 the thorax, as if for roUing-up. The groove separating the first from 

 the second pleura runs obliquely backwards and outwards at an 

 -single of about oO° to the front margin of the pygidium, curving 

 gently forwards at its outer end. 



Second pair of pleura3 distinct, each pleura increasing rapidly to 

 <louble the width possessed by the first pleura on the margin ; end 

 broad, truncated, and with posterior angle projecting beyond the 

 margin as a distinct tooth ; posteriorly marked oif by weak furrow 

 making an angle of about -lo^ with front margin of the pygidium. 

 A median, slightly oblique furrow traverses the surface of the pleura, 

 but stops short of the margin. 



The position of the projecting ends of this second pair of pleura? 

 • is about half-way along the lateral margins of the pygidium. Behind 

 them the margin takes a slight curve inwards to the points of the 

 posterior foric. 



The lateral lobes behind the second pair of pleural show no 

 -segmentation or fun-ows, but probably are composed of two pairs of 

 pleura?, one ending at the lateral pointed extremities of the posterior 

 margin and the other at the axal furrows in the re-entrant angle. 



A few scattered tubercles are visible on the flattened marginal 

 portion of the lateral lobes, especially near the posterior angles. 



Measurements. 



Leiig'th of head -shield 



"Width ot head-shield 



Leng'th of glabella 



AVidth of glabella at frout eud 



Widtli of glabella at level of eyes 



Width of glabella at iieck-fuirDW 



Width of thorax 



Width of axis of thorax 



Length of pygidium ... 



Width of pygidium at front end 



Width of pygidium between posterinr angles 



Width I if axis of pygidium ... 



I = Salter's specimen. II = Fletcher's specimen. 



N.B. — In the Fletcher specimen the hypostome is also seen in its 

 proper position on the lower surface of the upturned head. It is 

 subjDentagonal in shape; its length is less than its breadth, which 

 is greatest across the middle. Tlie central portion, which is also of 

 greater breadth than length, is marked off by a continuous furrow 

 from the border, is gently convex, and occupies about two-thirds of 

 the whole length of the hypostome ; its anterior end is strongly 

 arched forwards, and its sides and posterior edge are nearly straight 

 and parallel respectively to the lateral and posterior margins of the 

 hypostome. A pair of faint short furrows run obliquely inwards 

 from the lateral angles. The border is broad and flattened, extending 



