igoij Halkett— African Dipnoid Fish. 185 



" Ceratodns miolepis and C. forsteri, from the rivers of Queensland, 

 Australia. 



" Protopteriis aniiecteiis, from the rivers of tropical Africa. 



" The species alluded to in your columns is the last mentioned, Protop- 

 teriis annectens, of tropical Africa. Thisfish inhabits the rivers of that continent, 

 and while it has sufficient water there is nothing extraordinary concerning- its 

 function of respiration, as it breathes just like other fishes, by gills; but during 

 the dry season it encases itself in capsules of mud and mucus, and then 

 breathes through its lung. While tlius encased it can be transported alive to 

 great distances, and when replaced in water the gills again assume their 

 normal function. 



'The Dipnoids are a sub-order of the Ganoids, to which the sturgeons 

 and garpikes belong. I have seen sturgeons bre'ithing atmospheric air by 

 putting their snouts out of the water, and on examining a specimen of the 

 garpike found an approach to a rudimentary lung, the air-bladder being 

 cellular, thus revealing even in these North American fishes certain dipnoid 

 characteristics. 



" Petrified remains of other genera of Dipnoids are found in Devonian 

 formations."' 



Since the above was published I have been fortunate enough 

 to see several living" specimens of Dipnoids, during my visit some 

 time ago to Great Britain. Two of Ceratodus in one of the aquaria 

 of the Zoological Gardens, Regent's Park, London ; and one of 

 Protoptenis annectens in the aquarium of the Liverpool Public 

 Museum, which had been successfully transported from Africa in 

 its mud-capsule. Furthermore, Dr. P'orbes of the latter institution 

 very kindly gave me a specimen of Protopterus also encased in its 

 capsule, and which I brought with me across the Atlantic ; with 

 the intention of dissolving it, and liberating the fish on my arrival 

 in Ottawa. So of late I have had additional incentives for prose- 

 cuting my studies of the Dipnoids. 



The group receives its name from the double character of the 

 respiratory organisation : these remarkable fishes breathing not 

 only under water by gills, but at times, as has been stated in the 

 letter to the Gazette, when the waters dry up, atmospheric air by 

 rudimentary lungs. They belong to the Ganoid group of fishes, 

 and are referable to three existing genera : Ceratodus, Lepidosiren, 

 and Protopterus ; and to a few extinct ones. The existing species 

 differ exceedingly from other Ganoids in the character of the 

 paired fins ; there being in the pectorals and ventrals an axial skel" 



