4.84 ONISCID®. 
length of the two terminal appendages of the tail. Herr 
Schnitzler has, indeed, proposed to form it into a separate 
genus, Cylisticus, on account of the convexity of the 
terminal segment of the tail, the rectangular lateral 
termination of the segments of the body, and the curious 
character (to which he has first directed our attention) 
that each of the false feet, or branchial plates of the tail, 
are marked with small white spots at the base; whereas 
in the other species it is only in the first and second pairs 
of those organs that this character is to be found. These 
characters do not appear to us, however, to be of suffi- 
cient importance to warrant the establishment of a new 
genus for the P. /evis. 
Its colour is of a leaden grey, occasionally blotched 
with yellow on the sides. It is sluggish in its habits, 
and occurs commonly in stable-litter, and among grass at 
the bottom of walls. 
It occurs in England and Ireland. Kent, and the 
neighbourhood of London and Dublin, have been re- 
corded as the localities. 
