Cyprinidæ [Palæarct., India, North America]-- Cyprinina [Palæarct., India, N. America-- Labeo [India] 6 „ Barynotus [India] 2 „ _Abrostomus_ 2 „ Discognathus lamta[24] [India] 1 „ Barbus [Palæarct., India] 35 „ Rasborina [India] 1 „ Danionina [India]-- Barilius [India] 3 „ Abramidina [Palæarct., India, N. America]-- _Pelotrophus_ 2 „ _Kneriidæ_ 2 „ Osteoglossidæ [India, Australia, South America]-- _Heterotis_ 1 „ _Pantodontidæ_ 1 „ Notopteridæ [India] 2 „ ------------ 255 species. ============ Out of the 39 families or groups of freshwater fishes 15 are represented in the African region, or three more than in the Indian region; however of two of them, viz., the _Ophiocephalidæ_ and _Mastacembelidæ_, a few species only have found their way into Africa. On the other hand, the number of species is much less, viz. 255, which is only two-fifths of that of the known Indian species. The small degree of specialisation and localisation is principally due to the greater uniformity of the physical conditions of this continent, and to the almost perfect continuity of the great river systems, which take their origin from the lakes in its centre. This is best shown by a comparison of the fauna of the Upper Nile with that of the West African rivers. The number of species known from the Upper Nile amounts to 56, and of these not less than 25 are absolutely identical with West African species. There is an uninterrupted continuity of the fish-fauna from west to the north-east, and the species known to be common to both extremities may be reasonably assumed to inhabit also the great reservoirs of water in the centre of the continent. A greater dissimilarity is noticeable between the west and north-east fauna on the one hand, and that of the Zambezi on the other; the affinity between them is merely generic; and all the fishes hitherto collected in Lake Nyassa have proved to be distinct from those of the Nile, and even from those of other parts of the system of the Zambezi.