1877.] Zodlogy. 371 
tinct school in biology. His works on the Monera, the Rhizopoda, the 
Sponges, Infusoria, Acalephs, etc., besides his masterly drawings and ele- 
gant literary style, should be taken into account in judging of his influ- 
ence on the progress of zodlogy. — Ep. NATURALIST. 
Notes on THE Beaver.— Along the banks of the Grand River, 
Northwestern Colorado, in the year 1874, I had an opportunity of ex- 
amining the work of a colony of beavers. I was first apprised of the 
vicinity of these animals by noticing a timber-shoot or clearing scooped 
out from the willow-brake to the edge of the water. It had the appear- 
ance of having been recently used, and the dragging of the logs had 
hollowed out the channel down to the brink of the stream. Through 
this slide I passed into a grove composed of slender willows which 
formed an almost impenetrable thicket. About fifty feet from the river 
was a circular clearing where the animals had been at work. Here the 
trees were larger, and many of them had been cut off obliquely within 
six inches of the ground, almost as nicely as though done with a steel 
axe. The logs had been hauled away, leaving an opening in the dense 
thicket. Farther on, larger trees had been felled which were still re- 
maining, the majority of them measuring six and eight inches in diam- 
eter, and one tree, which had been completely severed, measured at least 
fourteen inches. The wood had been gnawed around the circumfer- 
ence, a few inches from the base, the deepest cutting having been 
done on the side next the water, so that the tree might fall in that direc- 
tion. A few, however, had been felled so as to fall away from the river, 
which fact serves to show that these animals are endowed with an in- 
stinctive sagacity nearly approaching reason; for if they were guided 
merely by ordinary animal instinct, no mistakes would be made. Does 
not the bird build her nest as perfectly the first time as after years of 
practice? On the contrary, the beaver seems to be benefited by ex- 
perience, and just as man arrives at proficiency through his mistakes the 
beaver profits by his errors. I noticed that wherever there were trees 
which had been felled some time past and fallen in the wrong direction, 
the newer work had been accomplished, without exception, in a sys- 
tematic manner, all of the logs being cut so as to fall toward the dam. 
As I passed along the bank of the stream, I observed about ten timber- 
oots, running parallel, at right angles to the course of the current, and 
Separated by about fifteen feet. The larger trees had been cut near the 
water and above the dam for the purpose of floating them down, to 
Save the labor of dragging from the interior. I must have interrupted 
them at their work, as some of the cutting was perfectly fresh, and large, 
damp chips lay profusely around trees which had not been entirely 
severed. In one place where a tree had been cut almost through, water 
was dripping from the notch, showing where a beaver had just been at 
work. I picked up several chunks of wood, six or eight inches in di- 
ameter and about as much in length, the ends being obliquely parallel. 
