1. Its affinity to the Europo-Asiatic region is indicated almost solely by three groups of Cyprinoids, viz., the _Cyprinina_, _Abramidina_, and _Cobitidina_. The development of these groups north and south of the Himalayas is due to their common origin in the highlands of Asia; but the forms which descended into the tropical climate of the south are now so distinct from their northern brethren that most of them are referred to distinct genera. The genera which are still common to both regions are only the true Barbels (_Barbus_), a genus which, of all Cyprinoids, has the largest range over the old world, and of which some 160 species have been described; and, secondly, the Mountain Barbels (_Schizothorax_, etc.), which, peculiar to the Alpine waters of Central Asia, descend a short distance only towards the tropical plains, but extend farther into rivers within the northern temperate districts. The origin and the laws of the distribution of the _Cobitidina_ appear to have been identical with those of _Barbus_, but they have not spread into Africa. If, in determining the degree of affinity between two regions, we take into consideration the extent in which an exchange has taken place of the faunæ originally peculiar to each, we must estimate that obtaining between the freshwater fishes of the Europo-Asiatic and Indian regions as very slight indeed. 2. There exists a great affinity between the Indian and African regions; seventeen out of the twenty-six families or groups found in the former are represented by one or more species in Africa, and many of the African species are not even generically different from the Indian. As the majority of these groups have many more representatives in India than in Africa, we may reasonably assume that the African species have been derived from the Indian stock; but this is probably not the case with the Siluroid group of _Clariina_, which with regard to species is nearly equally distributed between the two regions, the African species being referable to three genera (_Clarias_, _Heterobranchus_, _Gymnallabes_, with the subgenus _Channallabes_), whilst the Indian species belong to two genera only, viz. _Clarias_ and _Heterobranchus_. On the other hand, the Indian region has derived from Africa one freshwater form only, viz. _Etroplus_, a member of the family of _Chromides_, so well represented in tropical Africa and South America. _Etroplus_ inhabits Southern and Western India and Ceylon, and has its nearest ally in a Madegasse Freshwater fish, _Paretroplus_. Considering that other African Chromides have acclimatised themselves at the present day in saline water, we think it more probable that Etroplus should have found its way to India through the ocean than over the connecting land area; where, besides, it does not occur.