DISTRIBUTION AND HABITS 179 



In relation to the geographical distribution of Amphibia 

 the land of the world is divided into two divisions, the first 

 called Notogaea, consisting of Australasia and South America, 

 and the second called Arctogaea, including the rest of the 

 world. The Cystignathidae among the Arciferous Anura are 

 found only in Notogaea, entirely absent from Arctogaea. In 

 Notogaea Arcifera generally are predominant, forming 90 per 

 cent of the total number of Anura. In Australia Apoda and 

 Urodela are entirely wanting, a curious fact which seems to 

 show that this continent was cut off from the rest of the world 

 until after the evolution of Anura, which were able to extend 

 into it by their greater powers of locomotion. Only one species 

 of the Firmisternia occurs in Australia, namely a species of Rana 

 in Cape York peninsula. There is only one Amphibian 

 in New Zealand, namely Liopelma, one of the Discoglossidae. 



It is a well-known fact that true oceanic islands, that is, 

 islands surrounded by deep water, such as St. Helena, have no 

 Amphibia ; the class is represented in several island groups 

 of the Pacific to the east and north-east of Australia such as 

 the Solomon Islands, but these islands are connected by shoals 

 at no great depth with the Malay Archipelago and so with 

 Asia, and are therefore included in the Palaeotropical division of 

 Arctogaea. South America or the Neotropical region, differs 

 from the Australian in the presence of Apoda ; Urodela are 

 not entirely wanting, but they are represented only by species 

 of Spelerpes and Plethodon, genera which belong to North 

 America and have evidently extended thence into the southern 

 continent. Besides the Cystignathidae, Hylidae, and Bufonidne, 

 which occur also in Australia, there are Engystomatinae. A 

 few Raninae belong to this region, and they probably originally 

 came from the north, but in the forest regions of tropical South 

 America they have been modified into an arboreal sub-family, 

 the Dendrobatinae, found also in Africa and Madagascar. One of 

 the Aglossa, namely Pipa, occurs ; Discoglossidae, Pelobatidae, 

 and Dyscophinae are absent. 



Arctogaea or the northern world, in which are included India 

 and Africa, differs from Notogaea in the absence of Cystigna- 

 thidae. Its main divisions are two, the Periarctic, i.e. the great 

 expanse of land round the Arctic circle including Europe, 

 Northern Asia and North America, and the Palaeotropical 



