358 FISHES. 



be borne out by the fact that it is j)rovided Avith 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 deoxy- 

 genised 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 probably produced by the 

 passage of the air through the cesophagus when it is expelled 

 for the purpose of renewal. As the Barramunda has per- 

 fectly developed gills, beside the lung, we can hardly doubt 

 that, when it is in water of normal composition, and sufli- 

 ciently 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 comj)elled to sojourn in thick muddy water 

 charged with gases, which are the products of decomposing 

 organic matter (and tliis 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 Barramunda, in 

 fact, can breathe by either gills or lungs alone, or by both 

 simultaneously. It is not probable that it lives freely out of 

 the water, its limbs being much too flexible for supporting 

 the heavy and unwieldy body, and too feeble generally to be 

 of much use in locomotion on land. However, it is quite 

 possible that it is occasionally compelled to leave the water, 

 although we cannot believe that it can exist without it in a 

 lively condition for any length of time. 



Of its propagation or development we know nothing, 

 except that it deposits a great number of eggs of the size of 

 those of a newt, and enveloped in a gelatinous case. We 



