486 



rounded margin and a concave upper surface. The seg- 

 ments of the body have the posterior angles acute. The 

 third, fourth, and fifth segments of the tail are largely 

 developed, their lateral margins being continuous with 

 that of the sides of the body-segments. The terminal 

 segment of the tail is elongate-conic, and pointed at the 

 tip, with the upper surface slightly convex, and extending 

 to about one-third of the length of the outer division of 

 the terminal appendages of the tail, which are elongate, 

 slender, and pointed at the tip. The general colour is 

 iron-grey, with clear borders to the segments, and with a 

 row of ill-defined whitish spots on each side of the body, 

 parallel with the lateral margins. When alive, it rolls 

 itself into a perfect ball on being alarmed. 



Specimens taken near London (at Highgate ?) by Mr. 

 Francis Walker, are in the cabinet of the British Museum. 



