48 ISLAND LIFE part i 



never sit upon their eggs, but allow them to be hatched, 

 reptile-like, by the heat of the sand or of fermenting vege- 

 table matter; and lastly, the emus and cassowaries, in 

 which the Avings are far more rudimentary than in the 

 ostriches of Africa and South America. New Guinea and 

 the surrounding islands are remarkable for their tree- 

 kangaroos, their birds-of-paradise, their raquet-tailed 

 kingfishers, their great crown-pigeons, their crimson lories, 

 and many other remarkable birds. This brief outline being 

 sufficient to show the distinctness and isolation of the 

 Australian region, we will now jmss to the consideration 

 of the Western Hemisphere 



Definition and Characteristic Groups of the Near die 

 Region. — The Nearctic region comprises all temperate and 

 arctic North America, including Greenland, the only doubt 

 being as to its southern boundary, many northern types 

 penetrating into the tropical zone by means of the high- 

 lands and volcanic peaks of Mexico and Guatemala, while 

 a few which are characteristic of the troi^ics extend 

 northward into Texas and California. There is, however, 

 considerable evidence showing that on the east coast the 

 Rio Grande del Norte, and on the west a point nearly 

 opposite Cape St. Lucas, form the mos't natural boundary ; 

 but instead of being drawn straight across, the line bends 

 to the south-east as soon as it rises on the flanks of the 

 table-land, forming a deep loop which extends some distance 

 beyond the city of Mexico, and perhaps ought to be con- 

 tinued along the higher ridges of Guatemala. 



The Nearctic region is so similar to the Palsearctic in 

 position and climate, and the two so closely approach each 

 other at Behring Straits, that we cannot wonder at there 

 being a certain amount of similarity between them — a 

 similarity Avhich some naturalists have so far over-estimated 

 as to think that the two regions ought to be united. Let 

 us therefore carefully examine the special zoological fea- 

 tures of this region, and see how far it resembles, and how 

 far differs from, the Palsearctic. 



At first sight the mammalia of North America do not 

 seem to differ much from those of Europe or Northern 

 Asia. There are cats, lynxes, wolves and foxes, weasels, 

 bears, elk and deer, voles, beavers, squirrels, marmots, and 



