570 



MR, Y. DAY ON THE QEOGKA.PHICAL 



water fislies are said to have descended, it is assumed in a living 

 state ; but of the instances 1 have had unequivocal evidence of, 

 they were invariably dead, sometimes putrid. Proof of their 

 descending alive is yet wanting. Then it has been stated, on the 

 authority of Grmelin, that fish-eggs may be carried by aquatic 

 birds. It appears hardly credible that fish-eggs could be swal- 

 lowed by birds and subsequently extruded per anum with their 

 vitality intact. If the fish were ovi-viviparous, the mothers (in- 

 side whom were fertilized eggs) might be swallowed, and thus 

 the eggs might (?) be extruded with the vitality unimpaired. But 

 there are no Indian freshwater fishes which are ovi-viviparous; and 

 the aquatic bird which swallowed the unfertilized fish-eggs would 

 hardly assist in producingfish.es in distant localities. That some 

 birds might gorge themselves with fish- eggs, and having flown 

 some distance, might disgorge some, is not improbable ; and in 

 such a manner fishes might be distributed. In fact, in India we 

 see some marine forms of Siluroids in which the males carry about 

 the eggs in their mouths until the young are hatched. Water- 

 beetles are likewise believed to occasionally convey fertilized fish- 

 eggs from one piece of water to another, and sometimes without 

 destroying their vitality. 



Respecting river-systems, by commingling (due to changes in 

 level, or from other causes), enabling fish to migrate, such appears 

 to be very likely. One might take as an example how some of 

 the Himalayan streams go to the Indus and western coast of 

 India, and others descend to the Granges and pass to the Bay of 

 Bengal. Here a communication by their lateral branches might 

 occur during some period of flood. 



But I have shown that some fishes of the western coast of India 

 and Ceylon have a very peculiar distribution ; present along the 

 mountain-summits or some distance up their sides, they are absent 

 from the plains, but reappear in the Himalayas, in Burma, Siam, 

 the Malay archipelago, or China. 



The geographical distribution of the amphibious Oriental family 

 of Ophiocephalidse is well worthy of an attentive investigation. 

 Species extend through vast districts. Thus 0. striatus is found 

 throughout the fresh waters of the plains of India and Ceylon, 

 Assam, Burma, Siam, and in most o£ the islands of the Malay 

 archipelago. This would be one reason for believing either that 

 these freshwater fishes at a former period could inhabit the sea 

 and thus extend from island to island, or else that land once joined 



