MIGBATOBT PISHES OF ASIA. 199 



ing the functional character of a lung in the genus Geratodtis, 

 rendering it amphibious. 



Secondly. That this respiratory sac, which has the functional 

 character of a lung, is the homologue of the air-bladder or swim- 

 bladder of ordinary fishes. 



Thirdly. That the distiDguishing character of an amphibious 

 fish is that the blood is purified at a respiratory organ distinct 

 from the gills, receiving venous but returning arterial blood into 

 the general circulation. 



I propose in the present communication adverting more parti- 

 cularly to the following points : — 



First. That there are fishes in Asia which normally respire at- 

 mospheric air direct. 



Secondly. That these fishes possess respiratory organs having 

 a lung-like function, and which are distinct from the gills. 



Thirdly. That they are essentially amphibious, as their accessory 

 respiratory organs receive venous and return arterial blood into 

 the general circulation without such passing through the branchiae 

 or gills. 



Fourthly. That this accessory respiratory sac is certainly not 

 homologous with the swim-bladder of fishes, but may be with the 

 respiratory sac of amphibious reptiles. 



Prior to discussing these points I propose briefly relating how 

 I have been led, step by step, to these conclusions. 



Ten years since, having failed in my experiment of attempting 

 to introduce Trout by means of their ova into the waters of the 

 Neilgherry hills in Madras, I obtained the sanction of Govern- 

 ment to try whether fish from the plains would succeed. At first 

 I had great diflSculty in conveying them alive, when a native sug- 

 gested mixing mud with the water, and in this way many Ophio- 

 cephalidse were carried in safety up the hills. 



As it appeared to me that the existence of mud in large*quan- 

 tities in water would tend more to the destruction than preserva- 

 tion of the lives of fishes, by choking the gills and impeding circu- 

 lation, I was at a loss for an explanation. The native reason 

 was that they could not beat themselves about so much, an argu- 

 ment which seemed hardly sufficient to explain the circum^ 

 stances. 



During the monsoon months, when enormous quantities of rain- 

 water descend from the hills to the rivers of the plains, the fish 

 are often seen dead in large numbers, due either to the water 



