EEPOET OX THE ISOPODA. 81 



Falkland Islands. Serolis trilohitoides is said by Eights to inhabit the coasts of the 

 South Shetland Islands, as well as the neighbourhood of Cape Horn; the remaining species 

 seem to be restricted to the Strait of Magellan and the extreme south of Patagonia. 



It is possible that Serolis trilohitoides will eventually prove to be the same species 

 as Serolis cornuta from Kei-guelen ; the two are at least very closely allied. 



With this exception the species that inhabit Kerguelen are in every case quite 

 different from the South American species. Besides Serolis cornuta, two others inhabit 

 the shores of Kerguelen, viz., Serolis Jatifrons and Serolis sei)temcarinata ; the first of 

 these occurs also in comparatively deep water (210 fathoms) off the Crozets. Serolis 

 septemcarinata is common to all three groujis of Antarctic Islands, Prince Edward and 

 Marion Islands, the Crozets, and Kerguelen, — while Serolis cornuta was dredged off the 

 Crozets durinoj the cruise of the " Gazelle." 



Finally the shores of the southern and eastern parts of Austraha are inhabited by 

 six species o£ Serolis, viz., Serolis tubercidata, Serolis australiensis, Serolis longicaudata, 

 Serolis elongata, Serolis minuta, and Serolis pallida; these species, with the exception of 

 Serolis minuta, form, as has already been pointed out {ante, pp. 65, 66), a well marked sub- 

 division of the genus, differing more from either the Kerguelen or the South American 

 species than any of these do from each other. 



It is rather premature to draw any general conclusions from these facts, even with 

 regard to the distribution of the genus Serolis alone ; but it may at any rate be pointed 

 out that the distribution of this genus, as at present known, seems to necessitate the 

 division of the southern hemisphere into two distributional provinces, (l) an Antarctic, 

 reaching from South America to New Zealand, and (2) an Australian. 



The genus Serolis seems to attain to its greatest development in point of number of 

 individuals on the shores of Patagonia and at Kerguelen; v. Willemoes Suhm states Hhat at 

 Kerguelen Serolis forms no less than 20 per cent, of the Crustacean fauna ; and that " a 

 large species (Serolis cornuta) is the predominant and most characteristic form of all the 

 Crustacea in the shallow water of the Antarctic Islands." 



It is true that ' nearly as many species are now kuowTi from Australia as from 

 Patagonia, but the genus does not appear to form an important element in the fauna of 

 the first mentioned locality ; only a very few specimens, not more than two or three, of 

 any of the six species were obtained by the Challenger ; the fact that no sjiecies have 

 been pre'^dously described" either by resident naturalists or from collections made by 

 exploring vessels, also indicates the rarity of the genus in this region. In Patagonia, on 

 the other hand, there are not only a comparatively large number of species, but the 

 number of individuals is also great, though apparently not forming so important an 

 element in the fauna as at Kerguelen. 



1 Proc. Roy. Soc, vol. sxiv. p. 590. 



- With the sole exception of one specimen of Serolis tubercuhta described by Grube, as quoted above. 



(ZOOL. CHALL. EXP. — FAKT XXXHI. — 1884.) Kk 11 



