INDIAN EEGION. 



221 



versing this district are more nlSinerous from the south 

 than from the north, and carry the southern fishes far into 

 the temperate zone. The boundary of this region towards 

 the north-west is scarcely better defined. Before Persia 

 passed through the geological changes by which its waters 

 were converted into brine and finally dried up, it seems 

 to have been inhabited by many characteristic Indian forms, 

 of which a few still survive in the tract intervening be- 

 tween Afghanistan and Syria; Ophiocephalus and Disco- 

 gnathus have each at least one representative, Macrones has 

 survived in the Tigris, and Mastacembelus has penetrated as 

 far as Aleppo. Thus, Freshwater fishes belonging to India, 

 Africa, and Europe, are intermingled in a district which 

 forms the connecting link between the three continents. Of 

 the freshwater fishes of Arabia we are perfectly ignorant; 

 so much only being known that the Indian Discognathus 

 lamta occurs in the reservoirs of Aden, having, moreover, 

 found its way to the opposite African coast ; and that the 

 ubiquitous Cyprinodonts flourish in brackish pools of Northern 

 Arabia. 



The following is the list of the forms of freshwater fishes 

 inhabiting this region :i — 



1 In the following and succeeding lists, those forms which are peculiar to 

 and exclusively characteristic of, the region, are printed in italics ; the other 

 regions, in which the non-peculiar forms occur, are mentioned within brackets 

 r ]. 2 Lates calcarifer in India as well as Australia. 



