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 much 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 the body throughout. The two first segments . 
of thethorax are together about equalin length to the headin 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 1 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 uropoda articulate. 
The antennules and antenne 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 antenne 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 remaining thoracic appendages are not greatly 
elongate. The uropoda are as in Pleurogonium. 
Kerguelen, Christmas Harbour, 120 fathoms. 
Genus PLEUROGONIUM, Sars. 
1. PLEUROGONIUM ALBIDUM, 0. 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 in the anterior segments; the dorsal surface of each of these 
three segments is traversed by a narrow ridge. Between the 
