Hy2 GENERAL rRlXClPLES OE ZOOLOGY 



S'.irfarc o[\cn opposes impassaMe liarriers to most manimals: rising-, if il lead lo 

 llu' I'ornialion ol L;lacici"cil niounlain-ihaiiis; sinkiiiL;, wlu-ii ai'iiis ol tlic si'a are 

 foniu'd, which inlcrposc slrailsor liroailcr LH)dii.'S, imiiassulik' lo iiiosl niaiiinials, 

 bclwccn two Uinil areas. J)irds and slroni,'-llyin!^ iiist'ets are less alTecled liy 

 aU such cliaiiLjes; the niajorit\' ol them can lly o\er arms of the sea and motin- 

 tain-chains; there are liirds w hicli can e\"en cross the Alhinlie. 



The Six Primary Regions. — Of tlie systems of animal L;eO!j:rapliv |iroposed 

 that advocated 1)V Sclaler and \\'allaee finds most fa\-or. They dislin;.;iiish six 

 primary re,i;ions: (i) the pahcinlir, com])risin,L; all Eurojie, nortliern Africa as 

 far as the Sahara, and northern Asia lo the Himalayas; (2) ihc J-llliiopiaii, Africa 

 south of the Saliara; (^^) the (ir/cH/(.7, includiuL; u|>]>cr and farther India, southern 

 China, and the western >[ahiy Islands; (4) and (5) the }u\irclic and the nco- 

 ti-iipiiiil re,i,nons, which make up the American continent and are ch'vided at about 

 the northern Ijordcr of Mexico; (6) the AustndhDi, with, besides Australia itself, 

 the hirger and smaller islands of the Pacific Ocean and the INIalay Islands, cast 

 of Celebes and Lombok, 



(i) The Australian region is most sharply distinguished and bv man\- is set 

 apart as a distinct division called 'Notoga^a.' Its isolated gcograjihical ]iosilioii 

 together with the fact that it has long been separated from other countries 

 (apparently since the beginning of the tertiary) e.x])lains why only the oldest 

 mammals, the monotremes and marsupials, have entered the region, while the 

 placental mammals have not been able to follow. The marsu])ials, which in 

 the secondary period also inhabited the northern heniis]ihere, and were replaced 

 there in tertiary times by the placentals, were able to de\'ehip farther in the 

 Australian region. Australia and the adjacent ishuuls are thus the land of 

 marsupials, which have persisted elsewhere only in South America, the ojiossum 

 ranging north into the United States. On the other hand, at the time of dis- 

 covery Australia lacked all terrestrial placental mammals exce]it those (bats) 

 which were not restricted by water and the Murid:e, easily trans]iorted on iloating 

 wood. Two larger mammals, the wild dog (Caiiis diiii^o) and the pig of New 

 Guinea (Siis pii[>ii(U!ns), may have accom]ianied man, this being j>robable for the 

 dingo, although his remains occur in the jileistocene along with those of the 

 giant marsupials. Further peculiarities of the Australian region are the birds- 

 of-paradise in New Ciuinea, the egg-laying mammals (monotremes), and the 

 cassowaries and the Australian ostrich {Droimcus iiovirliollaiiditt). 



It is easily understood that the island grou]is of the South Sea (Lolvnesia) 

 ha\'c developed many faunistic peculiarities, as well as that an exchange of forms 

 may have taken place between the islands of the oriintal ]iro\ince and those 

 faunally related to Australia, and that 'Wallace's Line' (p. 34') is not so sharp 

 a boundary as was once thought (extension of marsupials into Celebes, of ]ila- 

 centals into the Moluccas). On the other hand the distinctness of New Zealand 

 needs mention. It is chstinguished from Australia b\' a large number of pectdiar 

 birds (Aplcryx and the extinct Dinornithiche"), rcpliies (the ancient Spliniodoii), 

 and molluscs. If the bats and mice be excepted, New Zealand lacks all native 

 mammals, even marsupials. 



(2) The Neotropical province (South and Central America) is, next to 

 Australia, the most sharply characterizi'd, and has also been set aside as a 

 special division 'Ncoga-a,' partly in \iew of its geological history; during the 

 cretaceous and early tertiary time it was separated from North America by the 

 sea and had develojied a peculiar fauna (e.g., gigantic edentates, no carni\ores). 

 These peculiarities disappeared towards the end of lire tertiary b\ the entrance 

 of carnivores and ungulates from the north and an extension of the edentates, 

 marsupials, humming birds, etc., to the northern hemisphere. To Neca-a 

 belong the platyrhine ai>es, the ealarrhinc to the Old World. Characteristic 

 edentates are the armadillos, sloths, and ant-eaters; the marsujiials are retire- 



