176 ZOOLOGICAL GEOGRAPHY. [part hi. 



agencies in the limitation of their range. Even among the 

 aerial bats, however, only one family- — the Vespertilionidae — is 

 truly cosmopolitan, the others having a more or less restricted 

 range. Neither are the Cetacea necessarily cosmopolitan, most of 

 the families being restricted either to warm or to cold seas ; but 

 one family, the dolphins (Delphinidae), is truly so. This order 

 however will not require further notice, as, being exclusively 

 marine the groups do not enter into any of our terrestrial 

 regions. The only other family of mammals that may be con- 

 sidered to be cosmopolitan, is the Muridae (rats . and mice) : yet 

 these are not entirely so, since none are known to be truly 

 indigenous in any part of the Australian region except Australia 

 itself. 



In the class of Birds, a number of families are cosmopolites, 

 if we reckon as such all which are found in each region and 

 sub-region ; but several of these are so abundant in some parts, 

 while they are so sparingly represented in others, that they 

 cannot fairly be considered so. We shall confine that term 

 therefore, to such as, there is reason to believe, inhabit every 

 important sub-division of each region. Such are, among the 

 Passerine birds the crows (Corvidae), and swallows (Hiruudi- 

 nidae);. among the Picariae the kingfishers (Alcedinidae) ; among 

 other Land birds the pigeons (Columbidae), grouse and partridges 

 (Tetraonidae), hawks (Falconidae), and owls (Strigidae) ; among 

 the Waders the rails (Kallidae), snipes (Scolopacidae), plovers 

 (Charadriadae), and herons (Ardeidae) ; and among the Swimmers 

 the ducks (Anatidae), gulls (Laridae), petrels (Procellariidae), 

 pelicans (Pelecanidae), and grebes (Podicipidae). 



In the class of Reptiles there are few absolutely cosmopolitan 

 families, owing to the scarcity of members of this group in some 

 insular sub-regions, such as New Zealand and the Pacific Islands. 

 Those which are most nearly so are the Colubridae among snakes, 

 and the Scincidae among lizards. 



There is no cosmopolitan family of Amphibia, the true frogs 

 (Eanidae) being the most widely distributed. 



Neither is any family of Freshwater Fishes cosmopolitan, 

 the Siluridae, which have the widest range, being confined 



