

ISOPODA. 11 



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 setae. 



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 

 setae, 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 polar is Hodgson (8), pp. 241-3. 

 Gnathia antarctica Richardson (12), pp. 3-4. 



Specific characters : 

 Male. 



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 setae. 



This species was first described by Dr. Studer from an immature specimen taken 

 off Patagonia. Miss H. Kichardson 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 antennae 

 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 



