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 , Pkiloscia , 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. Yaries 
much in colour, in size, and in the number of the joints of 
the outer antennae. 
