no 



A HISTORY OF FISHES 



nected in some way either with the diet or with the method 

 of feeding, has arisen quite independently several times. Each 

 of the large African lakes, Victoria, Nyassa, and Tanganyika, 

 contains some hundred or so species of Cichlids which are 

 found nowhere else, and each lake boasts a species with modified 



Fig. 47. DIFFERENT KINDS OF MOUTHS, 



A. Head of Elephant Mormyrid {Gnathonemus elephas), X ^ ; b. Of Gar-fish 

 {Tylosurus longirostris), X J ; c. Of Half-beak (H emir h amp hus imifasciatus), X \ ; 

 D, Of Thick-lipped Mojarra (Cichlaso?na lobochilus), X ^ ; e. Of Star-gazer 

 (Zaleoscopus tosae), x I ; f. Of Butterfly-fish {Chclmo lofigirostris), X ^ ; g. Of 

 Spoonbill or Paddle-fish {Polyodo7i spathula), X J. 



lips. The same feature occurs again in the Thick-lipped 

 Mojarra [Cichlasoma) of Lake Nicaragua in Central America, 

 and there can be little doubt that similar conditions in each 

 case, or perhaps the adoption of similar feeding habits, has 

 independently brought about the development of the same 

 peculiarity in quite unrelated fishes. In many fishes the lips 



