The American Beaver, (Castor canadensis), is a remarkable animal. In original thought it is equalled by few animals, and in industry by none. With the possible exception of the porcupine, it is the largest gnawing animal in North America, once was widely distributed, and its beautiful fur has been in demand ever since the days of the colonists. Unfortunately, the Beaver’s intelligence was directed chiefly to the building of dams, canals, and houses, and procuring an abundant supply of food-wood, rather than in providing itself with means of escape from its arch enemy—the man with a steel trap. Because of the constant demand for its fur, this animal has been so nearly exterminated throughout the United States that practically none remains save where they are rigidly protected. At present the largest colonies known are those in the Yellowstone Park, although in Canada 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 submarine 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, between 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 water.

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. In 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 Nature in which the production of all animal life is carefully balanced; for a part of the exhibition is composed of representative species of mammals that, in turn, prey upon the serpents, thus keeping even the destroyers of the smaller injurious creatures within bounds!

BRAZILIAN TREE PORCUPINE.

During the past two years the collection of rodents has been steadily growing in importance. The following is a list of the species on exhibition at the close of the year 1912:

RODENTS IN THE ZOOLOGICAL PARK.
HARES AND RABBITS (Leporidae)
Mexican Swamp Rabbit Lepus palustris.
Cotton-Tail Rabbit Lepus palustris mallurus.
Domestic Rabbits, various breeds (Nursery stock.)
SQUIRRELS AND MARMOTS (Sciuridae)
Thirteen-Lined Spermophile Spermophilus 13-lineatus.
Desert Spermophile Spermophilus leucurus.
Richardson Spermophile Spermophilus richardsoni.
Woodchuck Arctomys monax.
Prairie Dog Cynomys ludovicianus.
European Squirrel Sciurus vulgaris.
Mexican Squirrel Sciurus aureogaster.
Central American Squirrel Sciurus variabilis.
Cuban Squirrel Sciurus chrysurus.
Variable Squirrel Sciurus griseo-flavus.
Gray Squirrel Sciurus carolinensis.
Black Squirrel Sciurus carolinensis niger.
Fox Squirrel Sciurus ludovicianus.
White-Headed Squirrel Sciurus macrouroides.
Malabar Squirrel Sciurus malabaricus.
Chipmunk Tamicis striatus.
African Ground Squirrel Xerus capensis.
Flying Squirrel Sciuropterus volans.
BEAVERS (Castoridae)
American Beaver Castor canadensis.
KANGAROO RATS (Heteromyidae)
Kangaroo Rat Dipodomys merriami.
POCKET GOPHERS (Geomyidae)
Harsh-Coated Pocket Gopher Geomys hispidus.
DORMICE (Gliridae)
Squirrel-Tailed Dormouse Myoxus glis.
Lesser Dormouse Myoxus dryas.
English Dormouse Muscardinus avellanarius.
MICE AND RATS (Muridae)
Domestic Mouse—Unusual Color Phases Mus musculus.
Japanese Waltzing Mouse Mus musculus.
Black Rat Mus rattus.
Black-and-White Rat Mus norwegicus.
Gray-and-White Rat Mus norwegicus.
Porcupine Mouse Acomys cahirinus.
Egyptian Gerbille Gerbillus pyramidum.
Muskrat Fiber zibethicus.
Cotton Rat Sigmodon hispidus.
JERBOAS (Dipodidae)
Greater Jerboa Dipus aegyptius.
COYPU AND SPINY RATS (Octodontidae)
Coypu Rat Myocastor coypu.
Hutia: Cuban Tree Rat Capromys pilorides.
Short-Tailed Hutia Capromys browni.
PORCUPINES (Hystricidae)
Canada Porcupine Erethizon dorsatus.
Brazilian Porcupine Sphingurus prehensilis.
African Porcupine Hystrix cristata.
VISCACHAS AND CHINCHILLAS (Chinchillidae)
Viscacha Lagostoma trichodactylus.
AGOUTIS (Dasyproctidae)
Golden Agouti Dasyprocta agouti.
Gray Agouti Dasyprocta prymnolopha.
CAVIES (Caviidae)
Domestic Cavy Cavia porcellus.
Capybara Hydrochaerus capybara.
Patagonian Cavy Dolichotis patagonica.