xcii Eodentia. MAMMALIA. Rodentia. 
olco-min. is tlie principal woi'k, its object being' to 
fnrnisli an artificial pond, which shall render tiie 
water sufficiently and evenly deep as to protect the 
entrances to their lodges and burrows, which are 
partially submerged. 'I'his self-imposed task, seem- 
ingly, of building dams is one of the most astonishing 
things in connection with animal “ instinct,” sagacity, 
or intelligence. 'I'he animal naturally builds a bur- 
row, as any other, in which to rear the young, or 
retreat for protection. Besides tins, we see him 
exercising the ingenuity of an engineer in construct- 
ing a house with a submerged cellar, through which 
he reaches a close chamber, the integrity of which 
is dependent upon a steady level of the surrounding 
water; the water must be above the entrance, but 
below the floor. Does he anticipate the possibilities, 
or has he experienced a flood and its discomforts in 
his well-built home? One tiling is true: he con- 
structs. through immense labor, a dam which causes a 
stay of the water, and, by constant care and prompt 
repairing, the needed condition is fulfilled. Ills house, 
or lodge, is a sort of edifice for ordinary purposes, 
while the burrow is a more natural means of protec- 
tion. On the small grass islands that are seen in 
Beaver Meadows these houses are constructed ; they 
consist of immense piles of sticks and mud, formed 
into a dome-shaped hut. One measured by Mr. 
Morgan was sixteen feet in diameter at the water- 
line. The vertical height of the lodge from water 
level was four feet six inches. This lodge was opened 
by Mr. .Morgan, who found about one foot in thick- 
ness of the top “■ substantially solid.” The ground- 
plan showed a chamber seven feet and eight inches 
in length, and seven feet in breadth. The vertical 
height was a little over twelve inches. An entrance 
issuing from the pond was ten feet in length, another 
side entrance being seven feet in length. 'I'he roof 
was about three feet, and the side walls nearly five 
feet thick. “Among the characteristics of the 
Beaver,” says Mr. Morgan, “ is that of cleanliness, 
and nothing appeared in this chamber to detract 
from his reputation in this respect. 'J'here was no 
opening for light or ventilation ; but yet, from the 
porous nature of the materials, as put together, 
sufficient air would penetrate the lodge from without 
to satisfy the requirements of its occupants, whose 
low respiration enables them to endure the confined 
atmosphere of the lodge and burrow. 'I'heir l)reath 
in the winter season, rising through the top of the 
lodge, dissolves the snow, thereby e.xposing their 
habitation to the trapper.” 'I'he entrances, usually 
two, are the most remarkable parts of the edifice, be- 
ing constructed very skilfully, and even artistically. 
'Two kinds are seen : one is straight, or a.s nearly so 
as ]jossible, the floor being an inclined plane, rising 
gradually from the bottom of the pond to the cham- 
ber ; the other is abrupt in its inclination, and sinu- 
ous in its course. Mr. Morgan regards the first as a 
“ wood entrance,” from its evident design to facilitate 
the admission of “ wood cuttings,” upon which they 
subsist during the winter. 'I'he other entrance is for 
ordinary passage. 'These [jassages were rudely arched 
over with a roof of interlaced sticks, filled in with 
mud. intermixed with vegetable fibre, and were ex 
tended to the bottom of the pond and trench, with 
the e.xception of the openings at their ends. Where 
they joined the floor, they were constructed with 
neatness and precision, “ the upper parts and sides 
forming an arch more or less regular, while the bot- 
tom and floor edges were formed with firm and com- 
pacted earth, in which small sticks were embedded. 
It is difficult to realize the artistic appearance of 
some of these entrances without actual inspection.” 
The quantity of sticks used in the construction of 
this lodge was about a cord. In most instances the 
floor of the lodge is from two to six inches above 
the water. It is evident that some calculation is 
exercised to maintain a proper water level, as the 
“ cuttings ” which t\\ey prepare for food have to be 
carried by the Beavers down to the bottom of the 
pond, and thence up the inclined plane to the en- 
trance. Here they must drag the “cuttings” by the 
teeth up and into the lodge, depositing them upon 
the floor. Mow, if there is great discrepancy in the 
elements of structure, the Beavers may find it a diffi- 
cult feat to lift the “cuttings” by the teeth after 
they are out of water ; while immersed, the buoyancy 
is greatly in their favor. “ It is evident that the 
Beavers regulate the discharge of surplus water 
through their dams with a view to the maintenance, 
as nearly as possible, of a uniform level of the pond ; 
and great variation would either flood their habita- 
tions or ex[)Ose their entrances. * * * In all 
this, decisive evidence seems to be furnished of their 
possession of a free intelligence, as well as of con- 
structive skill.” 'There is usually a moat or ditch, 
about three feet wide, excavated around the lodge, 
opening on one side into the pond. 'The number of 
lodges in a large pond seldom exceeds four. 'The 
stories about lodges containing several rooms for 
special purposes are not true. Mr. Morgan regards 
the specimens of lodges that are double as the work 
of numerous individuals, and not by one pair. IMoro- 
over, these double houses do not communicate with 
each other, the rooms being entirely separate. 'The 
burrows are small underground chambers, usually 
constructed under the root of a tree, or entered from 
under a rock, and extend about fifteen feet into the 
bank of the stream or pond. 'I’hey are used, seem- 
ingly, exclusively for temporary protection, the en- 
trance being under water, and, no external mark be- 
ing visible, they furnish a surer hiding-place than 
the lodge, which is very conspicuous. Dr. Newberry, 
speaking of the Beaver lodges and burrows, says: 
“'The sides of the stream [in Oregon and California] 
are lined with their habitations. We found the 
Beavers in numbers, of which, when applied to 
Beavers, I had no conception.” One of the most 
remarkable feats, or instances of engineering skill, 
performed by the Beaver, will be considered when we 
have examined the nature of the food which it de- 
pends upon, and the conditions required for its pos- 
session. 'The Beaver is exclusively a vegetable eater, 
and subsists mostly upon the bark of deciduous 
trees, not upon that of the pines and other evergreens 
that grow in the low-grounds. It prefers birch 
