HAUNTS AND HABITATS 39 



of which one species inhabits Eastern China and the other 

 Eastern North America. This distribution seems at first sight 

 to preclude the Bering Strait route, but the migration may have 

 been earlier than that of the mammals, when the temperature 

 was higher. At any rate, it is difficult to invoke the aid of land 

 connections for modern types of reptiles which are not recog- 

 nised in the case of mammals. 



A remarkable feature in the distribution of reptiles is the 

 community between the faunas of Madagascar and South 

 America, as exemplified by certain snakes, iguanas, and fresh- 

 water tortoises. In the case of the tortoises the genus Podo- 

 cnemis is common to those two widely sundered areas, and the 

 same community of generic type holds good for certain snakes. 

 In the case of the tortoises it is possible to explain this re- 

 markable distribution by supposing that different members of 

 the genera in question travelled down the continents bordering 

 the two sides of the Atlantic, as extinct members of the group 

 are found fossil in the Eocene Tertiary rocks of the northern 

 hemisphere. On the other hand, certain extinct tortoises 

 (Miolania), of which no representatives are known in the 

 northern hemisphere, occur respectively in Queensland and 

 Patagonia. Their distribution it seems possible to explain 

 only by a connection of the southern continents and islands in 

 a southern zone ; and this being so, it is difficult to deny that 

 the Malagasy and South American species of Podocnemis have 

 not travelled by the same route ; — a route which may perhaps 

 best explain the distribution of the snakes and iguanas, despite 

 the fact that representatives of the latter are met with in a 

 fossil state in the European Tertiaries. It should be added 

 that certain genera of tortoises, such as Pelomedusa and Ster- 

 nothtzrus, are peculiar to Madagascar and Africa, thus bringing, 

 with the help of the aforesaid Podocnemis, the fauna of the 

 latter continent into connection with that of South America, 

 and so with Australia. 



Such are a few of the puzzling problems presented by the 

 distribution of reptiles ; but to dilate further on this subject is 

 impracticable, and I accordingly pass on to glance at some of 

 the leading features in the distribution of the more important 

 groups of reptiles. 



As regards the Chelonia, of which the northern range in 



