74 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



they form an outer lower lip. Each consists of an inner 

 rectangular plate spinose at its anterior margin, and an 

 outer five- jointed palp. The joints of the palp are spinose, 

 each of the four distal joints having on its inner side a 

 setose pad. At the base there is a small lamella. 



The pereiopods (PI. II., figs. 8, 9) or ambulatory- 

 appendages. Each pereiopod consists of a basal protopodite 

 and an endopodite, which is composed of five spinose joints 

 (ischiopodite, meropodite, carpopodite, propodite and 

 dactylopodite). In the posterior pairs of pereiopods, the 

 carpopodite and propodite are long in comparison with 

 the other joints. The dactylopodite bears two strong re- 

 curved claws. 



In the female each of the anterior five pairs of 

 pereiopods (PI. II., fig. 12) subtends a thin foliaceous 

 lamella which curves downwards and inwards, overlapping 

 the opposite and adjacent lamellae, and thus they form a 

 brood pouch in which the eggs are carried. These lamellae 

 are not out-growths of the limbs, but of the sterna. 



Abdominal appendages. There are five pairs of 

 abdominal appendages or pleopoda, and a terminal pair of 

 uropoda. Each pleopod (PI. II., figs. 11, 13) consists of a 

 pear-shaped superior lobe covering a small inferior lamella. 

 In the terrestrial isopods, the outer lobe is termed 

 opercular and the inner branchial. In Ligia both are 

 branchial, as will be shown later. 



At the base of the outer edge of the superior lobe, 

 there is a small lamella. The edge of the superior lobe is 

 fringed with a border of setose bristles. The second pair 

 of pleopods are modified in the male by having a two- 

 jointed style arising at the base of the inner margin of 

 the superior lobe (PI. II., fig. 10). The style is long and 

 grooved, and reaches to the fourth pleopod ; its distal 

 extremity is slightly swollen and finely pointed. It is 



