ISOPODA. i 
The telson is distinctly separated from the rest of the metasome, and is a long 
thin structure tapering near the extremity to a blunt point, which is provided with 
long sete. 
The uropoda are large, though the basal joint is small. 
The exopodite consists of a roughly cordate plate attached by its apex and 
almost completely conceals the proximal joint of the endopodite. The distal margin 
of this joint is indented. 
The endopodite is two-jointed ; a substantial proximal joint supports an ovoid 
distal joint, not quite so long, and the outer margin of this joint is supplied with long 
set, and these are longer and form a tuft at the extremity. 
The pleopoda are all much alike, the first pair are, however, stronger and very 
little larger than the others. 
Only two specimens of this species were taken in Winter Quarters inside the 
25-fathom line, one of them in a damaged condition. 
GNATHIA ANTARCTICA. 
(Plate I., fig. 2.) 
Anceus antarcticus Studer (18), p. 4. 
Gnathia polaris Hodgson (8), pp. 241-3. 
Gnathia antarctica Richardson (12), pp. 8-4. 
Specific characters :— 
Hale. 
Cephalosome quadrangular, with a strongly developed spine in front of each eye. Usually with 
two spines near the anterior margin and the middle line. 
Cephalosome and the anterior segments of the mesosome more or less spinous and fringed with 
long sete. 
This species was first described by Dr. Studer from an immature specimen taken 
off Patagonia. Miss H. Richardson identifies my G. polaris with Anceus antarcticus of 
Dr. Studer, which, when dealing with the Southern Cross collection, had escaped my 
attention. I have no reason to disagree with the identification. 
The male.—The cephalosome is broad, roughly quadrangular, with the postero- 
lateral margins rounded; the anterior border forms three crescentic lobes, of which 
the median is most prominent, but only visible when the mandibles are divaricated ; 
outside the more lateral lobes is a stout spur which is just external to the antenne 
and in front of the eye, it has a broad base and its anterior border is irregular if 
not toothed. The lateral portion of the cephalon is rather swollen but depressed in 
the centre. It is covered more or less completely with minute spines. 
The eyes are prominent and darkly pigmented. Immediately behind the 
cephalosome is a narrow crescentic segment, the first segment of the mesosome and 
one which does not reach the lateral margin of the body. The two following segments 
of the mesosome are short and broad, the next is attached by a distinct “ waist” and 
I 2 
