The boundaries of this zone have been indicated in the description of the Equatorial Zone; they overlap the southern boundaries of the latter in South Australia and South America, but we have not at present the means of exactly defining the limits to which southern types extend northwards. This zone includes Tasmania with at least a portion of South-eastern Australia (_Tasmanian sub-region_), New Zealand and the Auckland Islands (_New Zealand sub-region_), and Chili, Patagonia, Terra del Fuego, and the Falkland Islands (_Fuegian sub-region_). No freshwater fishes are known from Kerguelen’s Land, or from islands beyond 55° lat. S. The southern extremity of Africa has to be excluded from this zone so far as Freshwater fishes are concerned. This zone is, with regard to its extent as well as to the number of species, the smallest of the three; yet its ichthyological features are well marked; they consist in the presence of two peculiar families, each of which is analogous to a northern type, viz. the _Haplochitonidæ_, which represent the _Salmonidæ_, _Haplochiton_ being the analogue of _Salmo_, and _Prototroctes_ that of _Coregonus_; and the _Galaxiidæ_, which are the Pikes of the Southern Hemisphere. Although geographically widely separate from each other, the Freshwater fishes of the three divisions are nevertheless so closely allied that conclusions drawn from this group of animals alone would hardly justify us in regarding these divisions as sub-regions. One species of _Galaxias_ (_G. attenuatus_) and the three Lampreys are found in all three, or at least two, sub-regions. _Freshwater Fishes of the Southern Zone._ Tasmanian. N. Zealand. Fuegian. _Percichthys_ ... ... 3 Siluridæ-- _Diplomystax_ ... ... 1 _Nematogenys_ ... ... 1 Trichomycterina [Neotrop.] ... ... 5 _Gadopsidæ_ 1 ... ... (_Retropinna_ ... 1 ...) _Haplochitonidæ_ 1 1 1 _Galaxiidæ_ 6 5 4 Petromyzontidæ 3 1 3 -- -- -- 11 8 18