Subclass Dipneusti, or Lung-fishes 



6, 5 



They are known in Queensland as Barramunda. They inhabit the 

 rivers known as Burnett, Dawson, and Mary, reaching a length 

 of six feet, and being locally much valued as food. From the 

 salmon-colored flesh, they are known to the settlers in Queens- 

 land as "salmon." According to Dr. Gimther, "the Barra- 

 munda is said to be in the habit of going on land, or at least 

 on mud-flats; and this assertion appears to be borne out by 

 the fact that it is provided with a lung. However, it is much 

 more probable that it rises now and then to the surface of the 

 water in order to fill its lung with air, and then descends again 

 until the air is so much deoxygenized as to render a renewal 

 of it necessary. It is also said to make a grunting noise which 

 may be heard at night for some distance. This noise is proba- 

 bly produced by the passage of the air through the oesophagus 

 when it is expelled for the purpose of renewal. As the Barra- 

 munda has perfectly developed gills besides the lung, we can 

 hardly doubt that, when it is in water of normal composition 

 and sufficiently pure to yield the necessary supply of oxygen, 

 these organs are sufficient for the purpose of breathing, and 

 that the respiratory function rests with them alone. But 

 when the fish is compelled to sojourn in thick muddy water 

 charged with gases, which are the 

 products of decomposing organic 

 matter (and this must be the case 

 very frequently during the droughts 

 which annually exhaust the creeks 

 of tropical Australia), it commences 

 to breathe air with its lung in the 

 way indicated above. If the medium 

 in which it happens to be is perfectly 

 unfit for breathing, the gills cease to 

 have any function ; if only in a less 

 degree, the gills may still continue 

 to assist in respiration. The Barra- 

 munda, in fact, can breathe by either _, 



FIG. 386. Lpper jaw of Neocera- 

 gllls or lung alone or by both Simul- todus forsteri GUnther. (After 



taneously. It is not probable that Zlttel>) 



it lives freely out of water, its limbs being much too flexible 



for supporting the heavy and unwieldy body and too feeble 



