THE BEAVER. 565 



Lemmings are on their pilgrimage. While they are crossing the rivers or lakes, the fish 

 come in for their share of the banquet, and make great havoc among their columns. 

 It is a very remarkable fact that the reindeer is often seen in chase of the Lemmings ; 

 and the Norwegians say that the deer is in the habit of eating them. This statement, 

 however, seems to be rather of doubtful character. The termination of these extraor- 

 dinary migrations is generally in the sea, where the survivors of the much-reduced ranks 

 finally perish. Mr. Lloyd mentions that just before his visit to Wermeland, the Lem- 

 ming had overrun the whole country. The primary cause of these strange migrations 

 is generally thought to be hunger. It is fortunate for the country that these razzias 

 only occur at rare intervals, a space of some ten or fifteen years generally elapsing be- 

 tween them, as if to fill up the places of those which were drowned or otherwise killed 

 in the preceding migration. 



The Lemming feeds upon various vegetable substances, such as grass, reeds, and 

 lichens, being often forced to seek the last-named plant beneath the snow, and to make 

 occasional air-shafts to the surface. Even when engaged in their ordinary pursuits, 

 and not excited by the migratorial instinct, they are obstinately savage creatures. Mr. 

 Metcalfe describes them as swarming in the forest, sitting two or three on every stump, 

 and biting the dogs' noses as they came to investigate the character of the irritable 

 little animals. If they happened to.be in a pathway, they would not turn aside to 

 permit a passenger to move by them, but boldly disputed the right of way, and uttered 

 defiance in little sharp, squeaking barks. 



The color of the Lemming is dark brownish-black, mixed irregularly with a tawny 

 hue upon the back, and fading into yellowish-white upon the abdomen. Its length is 

 not quite six inches, the tail being only half an inch long. 



THE common BEAVER has earned a world-wide reputation by the wonderful instinct 

 which it displays, independently of its very great value in producing costly fur and 

 perfume. 



This animal is found in the northern parts of Europe and Asia, but is found in the 

 greatest profusion in North America. In days long gone by, the Beaver was an in- 

 habitant of our own island. It is generally supposed that there is but one species of 

 true Beaver, and that the Beaver of Europe and Asia is specifically identical with that 

 of America, even though certain small differences of fur and coloring may be Discerned 

 between them. The social Beaver of Northern America is a truly wonderfu. anima\, 

 displaying a singular mixture of reason and instinct, together with a curious absence 

 of both on occasions. The best account of this animal is to be found in Audubon and 

 Bachman's valuable work on the quadrupeds of North America, to which work I am 

 indebted for the following particulars. 



The Beaver lives in societies, varying considerably in number, and united together in 

 the formation of works which may fairly be considered as belonging to the profession of 

 the engineer. They prefer to make their habitations by small clear rivers and creeks, or 

 close to large springs, although they sometimes take up their abode on the banks of lakes. 



Lest they should not have a sufficient depth of water in all weathers and at all 

 seasons, the Beavers are in the habit of building veritable dams, for the purpose of 

 raising the water to the required level. These dams are composed of tree-branches, mud, 

 and stones, and in order effectually to resist the action of the water, are about ten or 

 twelve feet in thickness at the bottom, although they are only two feet or so wide at the 

 summit. When the different parts of the stream run with varying velocity, the forma- 

 tion of the dam is really a triumph of engineering skill, for wherever the stream is gentle, 

 the dam is built straight across it ; but wherever the current runs smartly, the dam is 

 curved so as to present a convex surface to its force. It often happens that when a 

 dam has been made for some years, its dimensions become very large, in consequence 

 of the trees and branches that are intercepted by it, and in process of time it sprouts 

 thickly with vegetation, and even nurtures trees of some dimensions. 



In forming the dam, the Beaver does not thrust the ends of the stakes into the bed of 

 the river, as is often supposed, but lays them down horizontally, and keeps them in their 

 place by heaping stones and mud upon them. The logs of which the dam is composed 



