436 PEOF. C. CHILTON ON DETO, A SUBANTARCTIC 



distinct from that genus. In his ' Crustacea Isopoda Terrestria ' (1885, 

 p. 233), he gave a diagnosis of the genus and included under it two species, 

 D. ecliinata, Guerin, and a new species D. acinosa, of both of which he had 

 examined specimens from South Africa in the St. Petersburg Museum ; 

 he mentioned also D. whitei, but stated that it is probably the same as 

 D. ecliinata. 



For many years after this no further addition was made to our knowledge 

 of this genus, but in 1906, Budde-Lund, having had an opportunity of 

 examining specimens of a Deto collected by the German Polar Expedition 

 at St. Paul's Island, in the Indian Ocean, gave a revision of the genus, 

 describing these specimens as a new species, D. armata, and established two 

 new species, D. magnifica and D. rohusta, on three specimens from the 

 Auckland Islands, New Zealand, preserved in the Dresden Museum. He 

 also assigned to the genus Deto a species that had been described in 1879 

 by Mr. G. M. Thomson under the name Actcecia aucUandice, and which, in 

 1901, I had provisionally placed under Scyphax ; also another species from 

 New Zealand described in 1885 by Filhol under the name Oniscus novce- 

 zealandice, and the species PUlougria marina, described by me in 1884 from 

 the East Coast of New South Wales. Budde-Lund thus gives eight species 

 under the genus, but of these, two, D. magnifica and D, rohusta, are, I think, 

 undoubtedly synonyms of D. auchlandia'. In 1910 I pointed this out and 

 stilted that two species of Isopoda, described from Chili by Nicolet in 1849, 

 namely, Oniscus huccidentus and 0. tuherculatus, were male and female 

 of a species of Deto, and were probably identical with 0. novce-zcalandia, 

 Filhol. 



Before the publication of Budde-Lund's paper in 1906, I had obtained 

 specimens of the two New Zealand species and had commenced a report on 

 the genus, describing the mouth-parts and the pleopoda, which, up to that 

 time, were practically unknown, as the only specimens available to Budde- 

 Lund in 1885 had been dried or poorly preserved. ]\Iy paper was long 

 delayed through lack of sufficient specimens of the different species, but 

 later on the Director of the South African Museum very kindly supplied 

 me with specimens of the two species found in South Africa, and 1 have 

 recently received additional specimens of D. novcc-zealandia^, Filhol, from 

 Stewart Island, New Zealand. I have thus been able to see specimens 

 of all the species that I consider to be good ones, except D. armata, 

 Budde-Lund, and in this paper I endeavour to give a fairly full account 

 of the genus. 



The genus is an extremely interesting one on account of the large size 

 and strikino- appearance of some of the species, the remarkable and varied 

 sexual differences, the strictly maritime habitat of all the species, and the 

 geographical distribution. 



