34 



THE COMMON FROG. [chap. 



capable of true flight, as also are those aerial existing 

 beasts the Bats, and as were those extinct reptiles 

 the Pterodactyles. Certain squirrels and opossums 

 can take flitting jumps by means of an extension 

 of the skin of the flank, and a similar, though much 

 greater extension, supported by elongated freely 

 ending ribs, is found in the little lizards {Draco) 

 called Flying Dragons. 



The class of Fishes supplies us, also, with an ex- 

 ample of aerial locomotion in the well-known Flying 



Fish. 



Since, then, every other class of vertebrate animals 

 (Beasts, Birds, Reptiles and Fishes) presents us with 

 more or fewer examples of the aerial species, we 

 might perhaps expect that the Frog class would also 

 exhibit some forms fitted for progression through 

 the air. We cannot say with certainty that such is 

 the case ; but Mr. Alfred Wallace, in his travels in 

 the Malay Archipelago, encountered in Borneo a 

 Tree-frog {Rhacophorus) to which he considers the 

 term "flying" may fairly be applied, and of which 

 he says, it "is the first instance known of a flying- 

 frog." Of this animal he gives us the following 



account : — 



" One of the most curious and interesting creatures 

 which I met with in Borneo was a large tree-frog 

 which was brought me by one of the Chinese work- 

 men. He assured me that he had seen it come 

 down, in a slanting direction, from a high tree as if 

 it flew. On examining it I found the toes very long 

 and fully webbed to their extremity, so that, when 

 expanded, they offered a surface much larger than 



