HANSEN: THE ISOPODA. 101 
pulchra, the fifth almost as large as the fourth, and its inner margin partly 
serrated; sixth and seventh joints much broader than in the preceding species. 
The epipod with the exterior margin evenly curved. 
Thorax. It was badly preserved, and therefore the relative breadth of the 
segments could not be drawn with so much certainty as could be wished. The 
want of processes and the scabrous surface are mentioned above. The three 
posterior segments, without any median dorsal impression not connected immov- 
ably with each other, and somewhat shorter than the four others together ; the 
last segment seems to be movably united with the abdomen. 
Thoracic Legs. The basal joint of the four anterior pairs anteriorly or ex- 
teriorly produced into an angle or short scabrous process. The first, pair (Plate 
II. Fig. 1) rather short and stout; the fifth joint conspicuously shorter than the 
second, compressed and somewhat expanded on the under side, the margin of 
which is hairy. Of the six other pairs of legs only the basal joint is preserved. 
Abdomen. It is nearly ovate and proportionally large compared with the 
thorax, but neither shape nor magnitude could be drawn with absolute cer- 
tainty, as the abdomen was roughly handled. The basal segment is very short; 
for the rest only a pair of very faint somewhat curved longitudinal impressions 
are seen on the scabrous dorsal surface. The operculum in the female without 
any keel. 
Uropods. Somewhat longer than in the preceding species, but of about the 
game shape. 
Size. The specimen described is about 25.6 mm. long, and 8.4 mm. broad. 
Habitat, Station 3413 (Lat. 2° 34’ N., Long. 92° 6 W.), 1360 fathoms, 
1 specimen. 
Remarks. It is easily distinguished from all other large species hitherto 
known by the general shape of thorax and abdomen, and the want of processes. 
CYMOTHOID Ai. 
As to the limitation and the constituent elements of this family I refer to 
the above named report on the Isopoda of the German Plankton Expedition. 
Of its six sub-families only two, namely, Æginæ and Cymothoinx, are repre- 
sented in the collection, the first sub-family by six, the second by one species. 
The leading work on these two sub-families is Shiödte and Meinert: Symbolæ 
ad Monogr. Cymothoarum, Crust. Isopod. Familia (Naturh. Tidsskr., 3 Re 
Bd. XII-XIV., 1879-84), and further remarks on the structure of the mouth 
and the classification are found in my above named work, Cirolanide, etc. 
In the large genus Alga Leach, not rarely several species are closely allied 
to one another, and three of the four species established here differ only in small 
features from species living in the most northern part of the Atlantic (in Nor- 
way, Greenland, etc.). In the following, some characters derived from the 
structure of the thoracic legs, and partly overlooked by earlier authors, will be 
used; besides, the shape of the posterior angles of the thoracic “ epimera,” of 
