1913] Zoo-Geography 11 



been proposed but that would be characterised only by a single 

 family of birds, the penguins, and it seems most advisable in 

 this paper to look upon it as a region of secondary rank, or else 

 to ignore it altogether. It seems to me also better to treat islands 

 having a decidedly distinctive fauna as portions of the realm to 

 v^hich they most nearly approach, rather than to consider them 

 as distinct, as there are all grades of such islands, and to recog- 

 nize one opens the way to an almost endless list of meager in- 

 sular realms. 



In this paper the distribution of land vertebrates only will 

 as a rule be taken into account, and greater weight will be given 

 to the occurrence of mammals, reptiles, and amphibians, than 

 to that of birds, as the latter, owing to their powers of flight 

 and migratory habits are less reliable indications of the zoolog- 

 ical character of a region than the former. Both fishes and 

 birds will however be used whenever it seems advisable. 



As the jSTorthern Realm is distinguished from the group of 

 four southern realms, more by the lack of the groups peculiar 

 to them than by the presence of distinctive forms of its own, I 

 will leave the discussion of its animals to the last, and take up 

 the southern realms first, in the order in which they have been 

 previously named. A further reason for this lies in the fact 

 that after discussing the realms in general, I shall treat the life 

 zones of Korth America, a portion of the ^NTorthern Realm, and 

 this arrangement allows me to approach this second part of my 

 subject in a natural and convenient way. 



The Australian Realm comprises not only Australia, ISTew 

 Guinea, and the neighboring islands as far west as Celebes and 

 Lombok, but also ISTew Zealand and the islands of Oceania, 

 which two last may be looked upon as outlying provinces and 

 taken up later. 



It is one of the most sharply characterised of the realms, its 

 main features being the presence here, and here only, of the egg- 

 laying mammalia, and the great development of marsupial mam- 

 mals and elapid serpents to the exclusion of other forms of 

 these groups, these being represented in Australia only by a few 

 rodents and bats on the one hand and a few harmless snakes on 



