AMPHIPODA AND ISOPODA FROM BARRINGTON TOPS. 87 



the BarriDgton Tops specimen comes pretty close to 

 Niphargus mortoni G. M. Thomson, 1 from Mount Welling- 

 ton in Tasmania, and I am almost inclined to look upon it 

 as a variety of this species. However, as there are several 

 other nearly allied species, with none of which our speci- 

 mens exactly agree, it will be safer to describe it in the 

 meantime as a new species. Niphargus mortoni was placed 

 under the genus Niphargus by Mr. G. M. Thomson with 

 considerable hesitation, for, as he pointed out, it differs 

 from that genus in several points, though Stebbing 2 in 1910, 

 leaves it under this genus. I agree with Mr. Geoffrey W. 

 Smith 3 that this species, as well as the others described 

 by him, are perhaps better placed under the genus Gam- 

 marus, since, except in the minute inner joint of the uropod, 

 they very closely agree with the species G. australis Sayce 

 and G. haasei Sayce, which certainly appear to be rightly 

 referred to Gammarus. 



The species now under consideration, on the whole seems 

 nearest to G. australis Sayce, but differs chiefly in being 

 less abundantly supplied with long setae. The following 

 description therefore will be sufficient. 



Specific Diagnosis. — Female. — Segments of the urus with 

 a few long setae on the dorsal surface, one or two small 

 ones being also found on the last two segments of the pleon; 

 on the last segment of urus there is a small spine in addition 

 to the long setae. Eyes small, oval. First four sideplates 

 deeper than their segments, nearly twice as deep as broad, 

 the inferior margin with a few short setae widely separated; 

 in the first sideplate these extend along a portion of the 

 anterior margin. Segments of pleon as in G. australis. 

 Upper antennae (fig. 4) about half the length of the body; 



1 Thomson, Proc. Roy. Soc, Tasmania for 1892, p. 24 (of separate copy). 



2 Stebbing, Australian Museum, Mem. 4, p. 641. 



3 G. W. Smith, Trans. Linn. Soc, Zool., vol. 11, p. 76. 



