DISTRIBUTION OF THE FAUNAS. 373 



much farther southward on the eastern shore, than on the 

 western. From the peninsula of Alashka it bends northwards 

 towards the Mackenzie, then descends again towards the Bear 

 Lake, and comes down near to the northern shore of New- 

 foundland. 



605. II. TEMPEBATE FAUNAS. The faunas of the tem- 

 perate regions of the northern hemisphere are much more 

 varied than that of the arctic zone. Instead of consisting 

 mainly of aquatic tribes, we have a considerable number of 

 terrestrial animals of graceful form, animated appearance, and 

 varied colours, though less brilliant than those found in tropi- 

 cal regions. Those parts of the country covered with forests 

 especially swarm with insects, which become the food of other 

 animals : worms, terrestrial and fluviatile mollusca are also 

 abundant. 



606. Still, the climate is not sufficiently warm over the 

 whole extent of this zone to allow the trees to retain their 

 foliage throughout, the year. At its northern margin the leaves, 

 excepting those of the pines and spruces, fall, on the ap- 

 proach of the cold season, and vegetation is arrested for a 

 longer or shorter period. Insects retire, and the animals 

 which live upon them no longer find nourishment, and are 

 obliged to migrate to warmer regions, on the borders of the 

 tropics, where, amid the ever-verdant vegetation, they find 

 the means of subsistence. 



607. Some of the herbivorous mammals, the bats, and 

 the reptiles which feed on insects, pass the winter in a state 

 of torpor, from which they awake in spring. Others retire 

 into dens, and live on the provisions they have stored up dur- 

 ing the warm season. The carnivora, the ruminants, and the 

 most active portion of the rodents, are the only animals that 

 do not change either their abode or their habits. The fauna 

 of the temperate zone thus presents an ever-changing picture, 

 which may be considered as one of its most important features, 

 since these changes recur with equal constancy in the Old and 

 the New World. 



608. Taking the contrast of the vegetation, as a basis, 

 and the consequent changes of habit imposed upon the deni- 

 zens of the forests, the temperate fauna has been divided into 

 tw r o regions ; a northern one, where the trees, except the 

 pines, drop their leaves in winter, and a southern one, where 

 they are evergreen. Now, as the limit of the former, that of 



