1 10 NATURE STUDIES 



their native rivers during the wet season ; but when 

 the dry season approaches, they bury themselves in 

 the mud, and lie there, baked as in a kind of mud-pie, 

 until the return of the persistent rains. During this 

 land-existence, their " lungs " come into play. So 

 long as they live in their native waters, they breathe 

 by their gills like ordinary fishes ; but, ensconced in 

 the mud, they breathe air directly from the atmo- 

 sphere, like ourselves. The air-bladder purifies the 

 blood, which the heart pumps into its vessels, and 

 from the " lungs " the purified blood is returned to 

 the heart. The fish is thus truly a " double-breather "; 

 it exhibits in itself the combination of the frog and 

 the fish. 



Dr. Giinther tells us that whilst the mud-fishes 

 remain in the " torpid state of existence, the clay- 

 balls containing them are frequently dug out, and, 

 if the capsules are not broken, the fishes im- 

 bedded in them can be transported to Europe, and 

 released by being immersed in slightly tepid water/' 

 The " Jeevine," with its similar ' ' lung," is said to 

 leave the Australian rivers at night, and to waddle 

 its way to the marshes and swamps, there to feed 

 upon the vegetable matter that forms its staple food. 

 In the nocturnal journeyings of the fish we can readily 

 perceive the utility of the " lung." 



It may lastly be remarked that other fishes are 

 known to leave the water and to exist for a time on 

 land. The climbing perch of India, and the Ophio- 

 cephali, also of India, illustrate such fishes; but in 



