36 A Guide to the Zoological Collections 



The Silurida also form a very large family ; they are 

 not exclusively inhabitants of fresh-water, for some 

 species live in estuaries and in the sea, but always 

 near coasts. Though some species occur in North 

 America, in Europe, in Central Asia China and Japan, 

 and in Australia, the great bulk of the family are found 

 in Tropical America, Tropical Africa, and Southern and 

 Tropical Asia. Sometimes {e.g., Arms) the same genus 

 is represented in Tropical America, in Tropical Africa, 

 and in India. 



The other true fresh-water fishes that are found in 

 India are 



(3) the Cyprinodontidce, little carp-like fishes that also 

 occur in Tropical America, in Tropical Africa, and in 

 some of the countries bordering on the Mediterranean : 



(4) the Chromides, a family of which most of the 

 members inhabit Tropical America, a considerable 

 number are found in Africa and Syria, and 2 species 

 only occur in India and Ceylon : 



(5) the Symibranchidce, a small family of fresh- water 

 eels occurring only in Tropical America, in the Indian 

 region, and in Australia : 



(6-9) the Notopteridac, the Labyrinthici, the Ophio- 

 cephalidce and the Rhyncholdellidce — all small families 

 that occur only in Africa and the Oriental region : 



(10) the Na?idina, a small subfamily of Perch-like 

 fishes peculiar to India. 



The fresh-water fishes of India thus show a curious 

 connexion with those of Tropical Africa and Tropical 

 America — a connexion that, if we can find other con- 

 firmatory evidence, would incline us to suppose that 

 the ancestors of the fresh-water fishes of India were 

 inhabitants of a great tropical sea that formerly 

 extended from Central America eastwards across 

 Africa far into Southern Asia. 



