CH. I] FROGS AND TOADS. 47 



are found in Madagascar, a state of affairs which is paral- 

 leled in some other groups. 



On the whole the snakes emphasise the necessity of 

 drawing a sharp line between the Old and New World, as 

 indeed do all the reptiles. 



Distribution of Batrachia. 



While the Urodele Amphibia are limited to the 

 northern hemisphere, the frogs and toads have a nearly 

 world-wide range ; the only places where they are uniformly 

 rare are true oceanic islands ; as will be explained, facilities 

 for crossing the sea are entirely wanting. The occurrence 

 therefore of a true frog in the Solomon islands is one of 

 the chief proofs, from the zoological side, that this island 

 is not a real oceanic island ; a species which occurs in that 

 island (there are eight others) is the largest of all existing 

 frogs and toads and is known as Rana guppyi. The Fiji 

 islands possess three species of the genus of frogs Comufer. 

 This family, the Ranidae, is nearly cosmopolitan ; but the 

 toads comprised in the family Bufonidse are more nearly 

 completely cosmopolitan. The tree frogs, Hylidse, are also 

 very widely distributed ; but as is natural they find their 

 greatest development in " Dendrogaea," the Neotropical 

 region. Oddly enough these often purely arboreal crea- 

 tures, some of which do not even lay their eggs in pools, 

 are totally absent from the forests of Africa, indeed from 

 the Ethiopian region altogether. The lowly organised 

 group of frogs, Aglossa, comprise two families, the Pipida3 

 and the DactylethridaB ; the latter are in more than one 

 particular near to the tailed Amphibians ; they are, for 



