176 
ZOOLOGICAL GEOGRAPHY. 
[part hi. 
agencies in the limitation of their range. Even among the 
aerial hats, however, only one family — the Yespertilionidse — 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 (Delphi nida?.), 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 Murid® (rats and mice) ; } et 
these are not entirely so, since none are known to be truly 
indigenous in an} r 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 Tegion 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 eveiy 
important sub-division of each region. Such are, among the 
Passerine birds the crows (Corvid®), and swallows (Hirundi- 
nidse) ; among the Picarise the kingfishers (Alcedinida?) ; among 
other Land birds the pigeons (Columbidse), grouse and partridges 
(Tetraonidae), hawks (Falcon id re), and owls (Strigidse) ; among 
the Waders the rails (Pallid®), snipes (Scolopaeidse), plovers 
(Charadriad®), and herons (Ardeid®) ; and among the Swimmers 
the ducks (Anatid®), gulls (Laridae), petrels (Procellariid®), 
pelicans (Pelecanid®), and grebes (Podicipid®). 
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 Colubrid® among snakes, 
and the Scincid® among lizards. 
There is no cosmopolitan family of Amphibia, the true frogs 
(Ranidce) being the most widely distributed. 
Neither is any family of Freshwater Fishes cosmopolitan, 
the Silurid®, which have the widest range, being confined 
