Africa, unlike India, does not possess either alpine ranges or outlying archipelagoes, the fresh waters of which would swell the number of its indigenous species; but at a future time, when its fauna is better known than at present, it is possible that the great difference in the number of species between this and the Indian regions may be somewhat lessened. The most numerously-represented families are the Siluroids, with 61 species; the Cyprinoids, with 52; the Mormyridæ, with 51; the Characinidæ, with 35; and the Chromides, with 29. There is not, therefore, that great preponderance of the two first families over the remaining, which we noticed in the Indian region; in Africa there is a comparatively greater variety of distinct Freshwater types, imparting to the study of its fauna an unflagging pleasure such as is scarcely gained by the study of the other region. With the forms peculiar to it there are combined those of India as well as South America. In Tropical Africa there are still remnants of Ganoids: _Protopterus_ (_Lepidosiren_) _annectens_ and _Polypterus bichir_, with the singularly modified _Calamoichthys_. The two former range from east to west, and are accompanied by an Osteoglossoid (_Heterotis_) which has hitherto been found in the Nile and on the West Coast only. Autochthont and limited to this region are the _Mormyridæ_, _Pantodontidæ_, and _Kneriidæ_, a singular type, somewhat akin to the Loaches. Of Siluroid genera the most characteristic are _Synodontis_, _Rhinoglanis_, and the electric _Malapterurus_; of Characinoids, _Citharinus_, _Alestes_, _Xenocharax_, _Hydrocyon_, _Distichodon_, _Ichthyborus_. The regions with which Africa (like India) has least similarity are, again, the North American and Antarctic. Its affinity with the Europe-Asiatic region consists only in having received, like this latter, a branch of the Cyprinoids, the African Carps and Barbels resembling, on the whole, more Indian than Europo-Asiatic forms. Its similarity to Australia is limited to the two regions possessing Dipnoous and Osteoglossoid types. But its relations to the two other regions of the equatorial zone are near and of great interest.