ISOPODA. 49 



The uropoda are large and opercular ; a prominent ridge runs round the structure 

 on all sides except the distal extremity ; anteriorly and internally this ridge is some 

 little distance from the edge and terminates in a point. The distal extremity is 

 incurved and supports a pointed ovoid exopodite. 



The endopodite is smaller, more regular in shape, and concealed by the exopodite. 



The pleopoda are all very much alike ; the exopodite and endopodite are elono-ate 

 lamellse, the former a little the shorter ; both have setose margins. The sexual 

 modification of the second pair in the male has already been alluded to. 



Six specimens were taken at various times, in Winter Quarters, at depths varying 

 from 20-125 fathoms. The largest of these was a dead male measuring 119 mm. 

 in length and 42 mm. across the third segment of the mesosome. The smallest was not 

 more than 13 mm. long. In the small specimen the mid-dorsal ridge is relatively 

 more prominent, the metasome is proportionately longer, and the posterior band of 

 sculpturing on the cephalosome is more strongly developed. 



In life they are of a dull brown colour and of sluggish habits. 



NOTASELLUS. 



Instituted in 1886 by Dr. Pfeffer for a species taken in South Georgia, this genus 

 now contains two species. 



NOTASELLUS AUSTRALIA 



Notasellus amtralis Hodgson (8), pp. 251-3 ; Eicharclson (12), p. 13. 

 Specific characters : 



Uropoda bi-ramous, longer than the urosome, which is approximately as long as broad, and 

 terminates in a small rounded lobe between them. 



Two specimens of this species were taken at Cape Adare from the root of a large 

 Laminarian, Lessonia yrandifolia, in 17 fathoms, February 24th, 1904. 



It has also been taken by the French Antarctic Expedition in the neighbourhood 

 of Graham's Land, the western side. 



AUSTRONANUS. 



Body ovoid, without distinct waist between any of the segments. 



Cephalosome large, with stout lateral projections bearing the small eyes. 



Second antenna. Peduncle 5 -jointed. 



Mesosome. Segments very uniform in structure. 



Metasome, a single joint the urosome. 



Pereiopoda, all ambulatory. 



Uropoda, minute, preterminal,* a single setose joint. 



This genus is quite distinct from any other hitherto recorded, superficially at least, 



* Notwithstanding nay protests the author insists on the use of this neologism. ED. 



VOL. V. 



