232 HISTORY OF BRITISH CRUSTACEA. 



gression ; when pursued along the bottom, it runs quickly, 

 but often stops suddenly, turns round, and becomes assailant. 



Gen. 116. ONISCODA, Latr. 



Caudal appendages long. Front legs largest; claws 

 bifid. Eyes moderate, somewhat vertical ; antennas four ; 

 the lower shorter than the bristle-bearing joint of the outer 

 pair. 



Oniscoda maculosa, Leach. Spotted Hog -louse. (Plate 

 XII. fig. 7.) — Body ash-coloured, varied and spotted with 

 brown. 



In the sea, among Algae. 



Fam. ONISCIDjE. 



The species of this family appear to have only one pair of 

 antennae ; the other pair being in a rudimentary state. Ab- 

 domen formed of six perfectly distinct segments ; the last 

 of these does not acquire the dimensions which it exhibits 

 in the other Isopoda, where it serves as a shield to the false 

 branchial feet ; it is, on the contrary, very small, and some- 

 times even rudimentary. Their legs are slender. 



The species of Oniscidce are not so aquatic as the other 



