PORCELLIO SCABER. 477 



spinose at the tip. The foot-jaws are formed of a pair 

 of large oblong plates, having an elongated horny sup- 

 port on the outside arising from their base. The ex- 

 tremity of each is furnished with a number of minute 

 teeth, the inner ones arising from a distinct but very 

 short lobe or division. 



The terminal appendages of the tail are robust, with 

 the outer division triangularly ovate, and extending 

 about half its length beyond the extremity of the telson 

 or terminal segment of the tail, which ends in a sharp 

 triangular point, having a groove along the middle of its 

 dorsal surface, and which completely covers and conceals 

 the elongated accessory plate of the base of the apical 

 appendages. 



The colour of this species is uniformly of a greyish 

 black or slaty grey, more or less strongly spotted with 

 yellow ochre or whitish buff. A nearly uniform salmon- 

 coloured variety also occurs, and it is very probable that 

 others of the supposed species figured by Koch may be 

 only varieties. 



In P. duUus of Koch, the pale spots are wanting, the 

 uniform colour being blackish. In his P. qffinis there 

 is a pale lateral line parallel to each side, running 

 through the whole of the segments of the body. 



The species runs with agility, and partially rolls itself 

 into a ball when alarmed. It has been observed feeding 

 on living caterpillars, frequenting moist places where 

 decaying vegetation is found, and even among sea-weed, 

 in company with Ligia, &c. We have also found it 

 partial to growing vegetables, and it appears to possess 

 a strong partiality for nearly ripe wall-fruit. It is very 

 widely distributed throughout England and Ireland. The 

 female may be found with eggs contained in the ventral 

 pouch throughout the year. 



