and curved upwards at the tip, and along the middle of each there 

 is a deep furrow. The pygidium is obscure, except the left margin, 

 which consists of segments similar to those of the pleurae, but they 

 extend three-tenths of an inch beyond it, showing that this part of 

 the animal must have been unusually large. Cephalic shield 

 entirely obliterated. 



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

 This specimen is from my own cabinet. 



Group A. No. 3. 



This specimen consists of an incomplete impression of the 

 thorax and pygidium of a very peculiar species ; the three lobes 

 are of equal size, and each tapers rapidly to a point. The edge of 

 one lobe is broken off, but when complete, the entire width at the 

 front margin would be about six-tenths, and the length only four- 

 tenths, of an inch. Each lobe is well-rounded, and would probably 

 have eight segments— the number cannot be clearly determined, 

 as they are filled up at the caudal extremity. There is no trace of 

 the head. If trilobites cast their shells at certain periods, like 

 crabs, this specimen may represent the dorsal portion of a cast-off 

 shell. 



Locality — Outerside, on the north-east of Causey Pike. From 

 Mr. Dover's cabinet. 



Group B. No. i. 



Body elongated oval, length eight-tenths, and width four-tenths, 

 of an inch. The cephalic shield, which is somewhat indistinct, 

 occupies nearly half the entire length of the body; the front 

 margin of the glabella is slightly pointed, and there is a small 

 triangular projection in the centre of the posterior margin, which 

 partly overlaps the first thoracic segment. The cheeks are small, 

 and the outer angle of the posterior margin seems to be furnished 

 with a minute spine. The front portion of the axis is three times 

 the width of the pleurse, but it tapers with a rapid curve, and 

 terminates in a slender needle-like spine, which reaches nearly to 

 the posterior margin of the caudal shield ; there are eight segments 



