REPORT ON THE ISOPODA. 35 



not project so far laterally, but are similar in structure; the surface of the thorax is quite 

 smooth. Between the last thoracic segment and the abdominal shield there is a distinct 

 segment as in Pleurogonium. The shape of the abdominal shield is rhomboidal, with a 

 shallow notch at the posterior extremity and two very deep notches laterally where 

 the uropoda are articulated; the antero-lateral margins are smooth, the postero-lateral 

 margins are beset with spines like the rest of the body except at the lateral and 

 terminal notches. 



The antennides (PL III. fig. 1) are about one-fourth as long as the antennae, both 

 appendages arise as already stated at the extreme lateral margin of the head, where there 

 is a notch for the basal joint of the antennules ; the antennules do not, however, arise 

 entirely from the upper side of the head, being overlapped by the anterior lobe of the 

 lateral region of the head as shown in PL II. fig. 11. The basal joint is stouter but 

 shorter than the following joint ; the third and fourth are both narrower and shorter 

 than the second joint; the flagellum consists of only two rather elongated joints. 

 The antennules of this species are quite like those of Pleurogonium (cf. PL III. 

 figs. 1, 8). 



The antennse (fig. 2) are rather more than half the length of the body. 



The basal joint is extremely small, the second joint is short and furnished with a 

 single spine on the outer margin close to its articulation with the third joint ; the latter 

 is comparatively long, with a row of spines along the outer margin similar to those which 

 border the body ; these only extend along the proximal two-thirds of the joint ; the 

 three succeeding joints of the peduncle are much more slender than the basal joints ; the 

 fourth is extremely short, the two following elongated. The flagellum is a little longer 

 than the distal joint of the peduncle ; its joints are few and elongated. 



The mouth appendages I am unable to describe, as they were hidden by the thoracic 

 appendages, except to remark that the mandible is furnished with a palp. 



The first pair of thoracic appendages (fig. 3) are stouter than the rest and chehform ; 

 the proximal joint has a few spines on the outer margin near to its articulation with the 

 succeeding joint ; there were six or seven of them, which decreased in length towards 

 either end of the row. In the succeeding thoracic limbs (fig. 4) there are also a few 

 similar spines upon the basal joints ; I noticed them in the three following pairs of limbs, 

 but not in the three posterior pairs ; in no case, however, were they so numerous as in 

 the chehform appendages. 



The uropoda are small and exactly resemble those of Pleurogonium ; these appendages 

 are displayed in a dorsal and ventral view in figs. 5, 6 ; they are biramose, and the larger 

 endopodite completely covers the small exopodite when the appendages are viewed from 

 below; the extremity of each of the branches are furnished with a few longish simple hairs. 



Station 149k, off Christmas Harbour, Kerguelen, January 29, 1874; depth, 120 

 fathoms. 



