CH. I] AFFINITY BETWEEN AFRICA AND EUROPE. 43 



interesting to notice that the lacertilian fauna of Africa 

 attaches itself to that of the western Palsearctic region ; it 

 has often been remarked that Europe is really African in 

 its affinities; this however has been to a large extent 

 disguised by the destruction of animal life or its removal 

 due to the glacial period. It will be remembered that 

 before the glacial period and during the interglacial 

 periods (?) there were Hippopotami, Hyaenas &c. in 

 Europe. Mr Boulenger unites Australia with the Oriental 

 region, an union which is confirmed by the consideration 

 of other groups of animals of some age, e.g. earthworms 

 and crocodiles, and is accepted by botanists. 



The Distribution of Crocodiles. 



The distribution of the Crocodilia is very interesting, 

 and on the whole fits in with the known laws of the 

 distribution of animals. Fortunately one of our foremost 

 authorities on the system of reptiles, Mr Boulenger, has 

 recently summed up the existing knowledge of the range 

 of the group in the British Museum Catalogue. He 

 allows seven genera, Oavialis, Tomistoma, Crocodilus, 

 Ostolcemus, Alligator, Caiman and Perosuchus. There are 

 eleven species of Crocodilus, three of Alligator, and five 

 of Caiman; the remaining genera consist of a single 

 species apiece. As might be supposed from the large 

 number of species into which it is divisible, the genus 

 Crocodilus has the widest range of all the Crocodiles. It 

 occurs in all the tropical regions of both the Old and the 

 New World. Alligator was believed until recently to be 

 confined to America; but the existence of a Chinese 



