LIGIA. 233 



members of this order. Most of them live always on the 

 ground, while others live long out of the water without 

 suffering. None of them however live long in very dry 

 places ; damp appears to be necessary to their existence. 



There are two divisions of the family : in the first, one 

 British species only occurs, the Ligia oceanica. The basal 

 joint of the last false legs is slender, elongated, and com- 

 pletely exposed, and ends in two much-elongated, style- 

 shaped appendages. In the second division, containing 

 Oniscus, PJriloscia, and Porcellio, the basal joint of the last 

 false legs is short, and does not reach beyond the end of the 

 last segment of the abdomen. 



Gen. 117. LIGIA, Fair. 



Outer antennae with the last joint compound ; inner an- 

 tennae very short. Caudal appendages, two on each side, 

 inserted close together at the tip of a small joint attached 

 to last segment of abdomen. 



Ligia oceanica, Linn. sp. Great Sea-Slater. (Plate 

 XIII. fig. 1.) — Back of segments rough with depressed 

 granules. Antennae not quite so long as the body. Varies 

 much in colour, in size, and in the number of the joints of 

 the outer antennae. 



