75 



on the axis, but five only appear to belong to the thorax, and the 

 remaining three to the pygidium. The segnaents of the pleurae 

 curve faintly backwards, and increase in length towards the 

 pygidium, in proportion as the axis decreases in width, so that the 

 entire width of the body is maintained until it terminates in a 

 semi-circular caudal shield. 



Group B. No. 2. 



On the same fragment of slate there is the hollow cast of another 

 trilobite, about half the size oi the one just described, and appar- 

 ently of the same species, as the general form and proportions are 

 alike in both. 



Locality — Randel Crag. From Mr. Dover's cabinet. 



Group B. No. 3. 

 This specimen is a good deal distorted, especially the head. 

 Length six-tenths, and width four-tenths, of an inch. The glabella 

 appears to have been small, and almost circular, while the cheeks 

 are large, swelling out in front beyond the margin of the glabella, 

 which is rather depressed. The thorax and the pygidium are 

 slightly rounded and well-defined, axal furrows deep ; axis double 

 the width of the pleurse in front, and tapering to a point at the 

 caudal extremity ; thoracic segments seven in number. The 

 body maintains its width nearly to the tail, caudal shield obtusely 

 pointed, and terminated by a small thread-like ridge, which extends 

 round the margin. 



Group B. No. 4. 



On the same fragment of slate there are the crushed remains of 

 another trilobite, apparently of the same species, but not more 

 than a third of the size. 



Locality — Buzzard Crag, on the north-west side of Skiddaw. 

 From Mr. Dover's cabinet. 



Group B. No. 5. 

 This is a very beautiful and almost-perfect specimen. The head 

 is nearly half the entire length of the body, well-rounded in front, 



