168 



FIRST LESSONS IN ZOOLOGY. 



It lives on the dead leaves of aquatic grasses, etc. The lo- 

 cal English name is " flat-head," the native name being 

 "harramundi." 



The African lung-flsh (Pig. 172) has two lungs. It lives 

 on leaves in the White Nile, the E"iger, and Gambia rivers, 

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



Fio. 171. — Oeratodus, or Australian Lung-libh. 



point.) 



^Ilit loll m uutuiL ends in a 



lung-fish (Lepidosiren) lives in the rivers of Brazil. These 

 three lung-fish, with their amphibious habits, whose allies 

 began to exist in Devonian times, long before the coal 

 period, unmistakably point to the appearance of a new and 

 higher type of vertebrate life, — the Amphibians, or Sala- 



FiG. iTZ.—Protopterus annectens, a Lung-flsh of Africa. (One third natural 



size.) 



manders, etc. If their limbs were stronger, jointed, and 

 divided into toes like those of a frog's, they would be able 

 to walk and live on land. The transition from a swimming 

 to a walking air-breathing animal is a remarkable one; yet 

 we should bear in mind that at first the tadpole is without 

 limbs and breathes by gills. 



LiTBRATTjEB. — Hyrtl : Lepidosiren paradoxa. Prag, 1845. — 

 Oiinther : Description of Ceratodus. PhU. Trans., 1871. 



