130 POPULAR OFFICIAL GUIDE. 



they are rigidly protected. At present the largest colonies 

 known are those in the Yellowstone Park, although in Can- 

 ada and the Northwest many still remain. 



The most wonderful thing about the Beaver is the manner 

 in which he builds dams, to make ponds deep enough for 

 his timber-floating operations, and to afford him a sub- 

 marine passage to his house. Give him a valley and a 

 stream of water, and he will gladly make a pond out of 

 whatever raw materials are at hand. He uses the four-foot 

 sticks from which he has eaten the bark for food, and with 

 these, and an abundance of mud, he will raise a good strong 

 dam to a height of four feet, and a width on the ground of 

 ten feet or more. The mud used is dug out of the bottom 

 and sides of his pond, and carried, while swimming, be- 

 tween his paws, with his front feet holding it against his 

 breast. The sticks used in the dam are thrust endwise into 

 the mud on top of the dam, and the mud used is patted 

 down with his fore feet. The tail is not used as a trowel, 

 but in swimming it is the Beaver's propeller. 



In captivity the Beaver is not wholly a satisfactory animal. 

 Like some human craftsmen, he positively declines to work 

 under observation, and performs nearly all his tasks at 

 night. He thinks nothing of gnawing down a tree a foot 

 in diameter, and cutting its limbs into pieces which he can 

 handle while swimming. If he can secure enough food- 

 wood of kinds of his liking, he eats little else. Besides 

 building dams to create ponds in which he can take refuge 

 when hard pressed, he constructs canals, and houses for 

 winter use. He also digs burrows into high banks ; but his 

 entrances to his various homes always are under w'ater. 



THE ECONOMIC RODENT-REPTILE COLLECTION. 



As an answer to a frequent question — "Of what use are 

 reptiles?" — a new collection has been installed in the 

 Reptile House. It is supplied with descriptive labels, and 

 serves several purposes. Tn the first place there is presented 

 an elaborate series of the small gnawing animals, or rodents, 

 a number of the species of which are highly injurious to the 

 interests of agriculturists ; secondly, the exhibition contains 

 a large series of those species of snakes that prey upon the 

 destructive rodents. — thus presenting for observation the 

 serpents" of marked economic value. Finally, the entire 

 series stands as a clear demonstration of the perfect logic of 



