268 FISHES 



branchus occurs and the other two are Indian. Spiny-finned 

 fishes (Acanthopterygii) are represented only by Cichlidse the 

 head-quarters of which are in Africa (15 of the genera with 

 140 species occur in South America, 30 genera in Africa), 

 and by a few small species of the perch-like Nandidae. 



Africa in its fresh-water fishes has some features in common 

 with South America and others in common with India, a fact 

 which harmonises with its geographical position between those 

 two regions. Characinidse, as already mentioned, are abundant, 

 the large and ferocious species of Hydrocyon or dogs of the 

 water (Plate XXIII., C) corresponding to the fierce Serrasalmo 

 of South America. Citharinus, the moon-fish of the Nile, on 

 the other hand, is a harmless herbivorous fish which with allied 

 species is confined to Africa. The whole of the family Mormy- 

 ridse is confined to Africa : it includes the eel-like Gymnarchus 

 of the Nile, which reaches a length of six feet. Carps are 

 abundant, many of the genera being the same as in India. 

 Cat-fishes (Siluridas) are also characteristic, some of the genera 

 being also American, others also Indian ; some genera are con- 

 fined to Africa and among these is the electric cat-fish, Malop- 

 terurus. Africa possesses one lung-fish, Protopterus, closely 

 similar to Lepidosiren of South America, while the only surviving 

 fringe-finned ganoids (Polypteridse) are found only in this 

 continent. Heterotis, one of the Osteoglossids, is found only in 

 Africa. A few species of toothed carps (Cyprinodonts) occur and 

 extend into southern Europe, Spain, Italy and the Balkan 

 peninsula. The most characteristic fresh-water fishes are the 

 spiny-finned Cichlidse which are especially well developed in 

 Lake Tanganyika. Lates is a fresh-water species of the sea- 

 perches (Serranidse) occurring in Egypt. The Labyrinthici, 

 distinguished by the labyrinthine organ above the gills, are 

 common to Africa and Southern Asia. There are three species 

 of serpent-head (Ophiocephalus), eleven of climbing perches 

 (Anabantidse), and one of the gourami family (Osphromenidre). 



The Indian region, including southern Asia as far as the 

 island of Borneo, has no lung-fishes or Ganoids ; it is the head- 

 quarters of the carp family (Cyprinidae) ; cat-fishes (Siluridre) 

 are also very abundant with a large number of genera peculiar 

 to this region. One genus of Cichlidse occurs, namely, Etroplus. 

 Labyrinthici are well represented; of Symbranchidse Amphip- 



