152 



ZOOLOGY. 



ness, and is covered with round scales. The pectoral and 

 ventral fins are long, narrow, and pointed, and the verte- 

 bral column extends to the end of the caudal fin, which 

 ends in a point, not being two-lobed as in other fishes. 



The Australian lung-fish (Fig. 195) has but a single lung, 

 It attains a length of six feet. It can breathe either by- 

 gills or lungs alone. Ordinarily it uses its gills, but when Ihc 



Fig. 194.— Spoon-bill fish. From Lutken's Zoology. 



fish is compelled to live during droughts in thick muddy 

 water charged with gases which are the product of decom- 

 posing organic matter, it is obliged to use its lungs. It 

 lives on the dead leaves of aquatic grasses, etc. The local 

 English name is "flat-head/' the native name being "bar- 

 ramundi." 



The African lung-fish (Fig. 19G) has two lungs. It lives 



Fig. 195.— Ceratodus, or Australian Lung-fish. (The tail in nature ends in a 



point.) 



on leaves in the White Nile, the Niger, and Gambia rivers, 

 where it buries itself in the mud a foot deep. A similar 

 lung-fish (Lepidosiren) lives in the rivers of Brazil, and 

 the closely allied Protopterus in tropical Africa. Cerutoihts 

 makes use of the lungs mainly when the muddy water is 

 saturated with gases from organic matter. 



Finally we come to those American Ganoids whose skelc- 



