and NandinaB, SymbrancMdx, Notopteridse, Lahijrinthid, Opliioceitlialidx, Bhyncho- 

 hddlidse. Excluding tlie Carps and tlie Nandinie, we have our attention at once 

 attracted by certain curiosities of distribution. 



For instance, in tlie small family of Symhranchidse., we find Sijmbranchus 

 with three species, one common in the jheels of the Oriental region, another 

 common in tropical America. The third is from Indo- Australian waters. 



Again, the Gyprinodontidas, of which 2 genera and 5 species occur in India, 

 have a most suggestive range, being found in tropical and temperate America, 

 in tropical Africa and the regions of the Mediterranean basin, and in south- 

 western Asia — one genus, Cyprinodon, being represented in India and all round 

 the Mediterranean. 



Again, the Siluroid genus Arius has a tropical distribution that fits in most 

 remarkably with the theory of a tropical Mediterranean of wide extent east and 

 west. 



The same is the case with the Chromides, which are freshwater fishes of 

 tropical America and Africa, and of which three species are found in India. 



The other families — Notopteridse, Rhyncliohdellidx, Labyrinthici and Ophioce- 

 pJialidx — do not extend further to the west than "Western Africa. 



I may conclude this Introduction with some Tables of genera and species 

 that are common, on the one hand to the Atlantic and Mediterranean and, on 

 the other hand, to the seas of India. Of course many of these are widely ranging 

 forms, and may be discounted ; but, on the other hand, no mention is made of 

 several characteristic Indo-Pacific genera that have been discovered, fossil, in 

 the Tertiary deposits of Northern Italy, and a respectable number of forms that 

 are common to the Atlantic, the Mediterranean and Japan are not included 

 here. 

 I. List of Genera and Species common to the Atlantic, the Mediterranean, and the Indian Fauna. 



