488 ONISCIOE. 



Kinahan, having been confounded with P. scaber, from 

 which, however, it is at once distinguished by its more 

 elongate form, less rugose surface, and especially by the 

 narrowness of the tail, in which respect it approaches 

 the species of the genus Philoscia. The posterior angles 

 of the three anterior joints of the body are obtuse, and 

 those of the following joints are much less acutely pro- 

 duced backwards than in most of the other species of 

 the genus. The lobes of the head are but slightly pro- 

 duced, the central one being small and rounded. The 

 tail is small, the three principal segments being com- 

 paratively minute, as compared to their size, in the 

 preceding species. The terminal joint is short and 

 triangular, its extremity only extending a little beyond 

 the base of the terminal division of the apical appen- 

 dages of the tail, which is considerably elongated, as are 

 also the legs ; the whole structure of the animal indi- 

 cating greater activity and powers of movement. 



The variety P. maculicornis of Koch is of an iron 

 colour, with the outer antennae ringed with white, the 

 segments of the body having the posterior margins 

 simply granulated, and the terminal appendages of the 

 tail of a ferruginous colour. 



The species is of an uniform mouse-grey colour, seen 

 under a lens to be marked with white. It generally con- 

 ceals itself rapidly from the light, but, when disturbed, 

 runs with great rapidity. It prefers moderately humid 

 warm situations, and occasionally buries itself in the 

 earth, even in clayey localities, to a considerable depth. 

 It is very common both in England and Ireland. The 

 neighbourhoods of Dublin and Chiselhurst, Kent, are 

 localities in which they are found. It is equally plen- 

 tiful in the vicinity of Oxford. 



