393 



and inner branches, which act as gills, the outer branch of 

 the fourth being stouter, and forming an operculum divided 

 by a transverse suture. The terminal appendages, or urppoda, 

 are small and of the usual character, consisting of a short 

 basal joint and flat inner and outer branches. 



The whole of the species of the genus known up to 1884 

 were fully worked out by Mr. F. E. Beddard in his Report 

 on the Isopoda of the "Challenger" Expedition, in which he 

 also considered the geographical distribution of the group, 

 pointing out that the species are confined almost entirely to 

 the Southern Hemisphere, and have probably arisen on the 

 shores of the South Polar Continent and thence spread 

 northwards. 



Mr. Beddard also drew attention to the fact that the 

 six species then known from Australia form a well-marked 

 division of the genus, being characterized by the fact that the 

 tergum of the fifth segment of the peraeon is extremely 

 narrow and that of the sixth obsolete in the middle line, and 

 that all the species are of small size. 



Very little has been added to our knowledge of the group 

 since the publication of Mr. Beddard's paper. All the six 

 Australian species were obtained by Mr. Waite on the 

 "Thetis" Expedition, and were recorded in 1901 by Mr. T. 

 Whitelegge in his Report on the Isopoda. In one or two cases 

 he gave additional facts regarding their size and structure. 



In the collection belonging to the South Australian 

 Museum four of these species are represented, viz., S. tuber- 

 culata, S. australiensis , S. longicaadata, S. minnta, and there 

 are also specimens which I am describing as a new species, 

 S. bakeri, closely allied to Serolis minuta. The other two 

 Australian species are S. elongata and S. pallida. I have 

 seen no specimens of the latter, but I have been able to 

 examine a specimen of S. elongata in the collections made by 

 the F.I.S. "Endeavour." 



I give below a few additional notes and figures of some 

 of the species where they appear to be necessary, but there 

 is comparatively little to be added to the very full account 

 given by Beddard in 1884. 



Genus Serolis, Leach, 1818. 

 List of Australian species, with localities : — ■ 

 Serolis tubereulata, Grube, 1875. 



Bass Strait (Grube) ; Bass Strait, 38-40 fathoms ("Chal- 

 lenger," Stations 161 and 162) ; Newcastle Bight, 24-27 

 fathoms ("Thetis," Station 33); Gulf St. Vincent, 4 

 fathoms (Edgar R. Waite) : St. Francis Island, South 

 Australia, 6-13 fathoms (Dr. J. C. Verco). 



