612 FISHES, 



VIII. DiSTicHODONTlNA. — Dorsol fill ratluT elongate ; adi- 

 pose fin present. Gill-memhranes attached to the isthmus; 

 helly rounded,. Tropical Africa. 



Tlie species, ten in number, belong to one genus only 

 (Bistichodus), well known on the Nile under the name of 

 " Nefasch." They grow to a considerable size, being some- 

 times four feet long and one and a half foot deep. They are 

 used as food. 



IX. ICHTHYBOEINA. — An adijjose fin; nurnher of dorsal 

 rays increased (12-17) ; gill-membranes free from the isthmus. 

 Belly rounded ; canine teeth. Tropical Africa. 



Two genera only : Ichthyhorus from the Nile, and Phago 

 from West Africa, Small fishes of very rare occurrence, 



X. Crenuchina. — Dorsal fin rather elongate ; an adipose 

 fin. Gill-memhranes free from the isthmtis, ivith the hclly 

 rounded, and without canine teeth. 



This small group is represented in the Essequibo by a 

 single species, Crenuchus spilurus, and liy another in West 

 Africa, Xenocharax spilurus. 



XI. Serrasalmonina, — Dorsal fin rather elongate; an 

 adipose, fin. Gill-menibranes free from the isthmus ; helly 

 serrated. Tropical America. 



Although the fishes of this family do not attain any con- 

 siderable size, the largest scarcely exceeding two feet in 

 length, their voracity, fearlessness, and number renders them 

 a perfect pest in many rivers of tropical America, In all, the 

 teeth are strong, short, sharp, sometimes lobed incisors, ar- 

 ranged in one or more series ; by means of them they cut off 

 a mouthful of flesh as with a pair of scissors ; and any animal 

 falling into the water where these fishes abound is immedi- 

 ately attacked and cut in pieces in an incredibly short time. 

 They assail persons entering the water, inflicting dangerous 

 wounds before the victims are able to make their escape. 



