_Heteropygii_ 0 „ 2 „ Cyprinidæ-- _Catostomina_ 1 „ 25 „ Cyprinina [India, Africa] 80 „ 30 ” _Leuciscina_ 60 „ 70 „ _Rhodeina_ 10 „ 0 „ Abramidina [India, Africa] 44 „ 10 ” Cobitidina [India] 20 „ 0 ” _Hyodontidæ_ 0 „ 1 „ Petromyzontidæ [Southern Zone] 4 „ 8 ” ----------------------------- 360 species. 339 species. ============================= A. THE EUROPO-ASIATIC (PALÆARCTIC) REGION.--Its western and southern boundaries coincide with those of the Northern Zone, so that only those which divide it from North America have to be indicated. Behring’s Strait and the Kamtschatka Sea have been conventionally taken as the boundary, but this is shown to be artificial by the fact that the animals of both coasts, as far as they are known at present, are not sufficiently distinct to be referred to two distinct regions. As to the freshwater fishes those of North-western America and of Kamtschatka are but imperfectly known, but there can be little doubt that the same agreement exists between them as is the case with other classes of animals. The Japanese islands exhibit a decided Palæarctic fish-fauna, which includes Barbus and Cobitioids, forms strange to the North American fauna. A slight influx of tropical forms is perceived in the south of Japan, where two Bagrina (_Pseudobagrus aurantiacus_ and _Liocassis longirostris_) have established themselves for a considerable period, for both are peculiar to the island, and have not been found elsewhere. In the east, as well as in the west, the distinction between the Europo-Asiatic and North American regions disappears almost entirely the farther we advance towards the north. Of four species of the genus Salmo known from Iceland, one (_S. salar_) is common to both regions, two are European (_S. fario_ and _S. alpinus_), and one is a peculiarly Icelandic race (_S. nivalis_). As far as we know the Salmonoids of Greenland and Baffin’s Land they are all most closely allied to European species, though they may be distinguished as local races. Finally, as we have seen above, the Europo-Asiatic fauna mingles with African and Indian forms in Syria, Persia, and Afghanistan. _Capoëta_, a Cyprinoid genus, is characteristic of this district, and well represented in the Jordan and rivers of Mesopotamia.