1886.] DURING THE VOYAGE OF H.M.S. 'CHALLENGER.' 101 



extreme lateral margin ; eyes are absent. The thoracic segments 

 are separated by deep incisions ; the first segment is mnch the 

 largest, and is fused mesially with the following segment ; the 

 margins of the segments are rounded ; and the whole body is fringed 

 with numerous leaf- like flattened spines. 



1 . Neasellus kerguelenensis, F. E. B., loc. cit. 



The extreme length of the single individual of this species is 



2 millim. 



The body is extremely flattened and depressed, pear-shaped 

 in general outline, being much broader anteriorly than pos- 

 teriorly. The head is immensely extended laterally, being as wide 

 as the following segment of the thorax, from which, however, it is 

 separated by deep lateral incisions. The central region is convex ; 

 the anterior and lateral margins are fringed with peculiar flattened 

 spines, which also border tiie body throughout. The two first segments 

 of the thorax are together about equal in length to the head in its middle 

 region ; the line of suture separating these two segments is obliterated 

 except laterally ; the remaining segments are short and subequal, each 

 is about i of the length of the conjoined anterior segments ; the third, 

 fifth, and sixth segments have lateral processes, fringed with the 

 peculiar spines referred to, which are absent from the fourth and 

 seventh segments. The shape of the abdominal shield, which is, 

 as in Pleurogonium «&c., separated from the last segment of the 

 thorax by a single free abdominal segment, is rhomboidal ; it is 

 notched posteriorly and laterally where the uiopoda articulate. 

 The antennules and antennce arise from the extreme lateral margin 

 of the head ; in the antennules the basal joint is short and stout, the 

 second rather elongated, the third and fourth narrower and shorter 

 than the second, the flagellum has two joints. The antennce are 

 more than half the length of the body, the peduncle has six joints, 

 the flagellum is a little longer than the distal joint. The mandibles 

 are furnished with a palp. The first thoracic appendages are 

 cheliform, the i-emaining thoracic appendages are not greatly 

 elongate. The uropoda are as in Pleurogonium. 



Kerguelen, Christmas Harbour, 120 fathoms. 



Genus Pleurogonium, Sars. 

 I. Pleurogonium albidum, n. sp. 

 This species is represented by a single female example measuring 



3 millim. 



The general shape of the body is like the other species de- 

 scribed by Sars ; the epimera of the first four thoracic segments 

 are prolonged into spines, which are of equal size upon all the 

 segments ; the three posterior segments of the thorax are separated 

 from each other and from the fourth by deep lateral incisions ; their 

 epimera are prolonged into stout spiny processes, which are shorter 

 than jn the anterior segments ; the dorsal surface of each of these 

 three segments is traversed by a narrow ridge. Between the 



