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facets of the sloping planes were con vex and divided from each 
other not by ridges, but by furrows that do not always run 
parallel to each other. In the continuation of these furrows the 
branches are apt to split in the long direction. Fig. 3 represents 
in natural size the formed end of the largest and finest of the 
branches from Nørre Lyngby, 1 have found branches very much 
like them in a few of our postglacial bogs, and in Fig. 4 is re¬ 
presented in natural size a branch recently found by Dr. Knud 
jKSSfiiN in a mud-layer („gytja“), deposited during the temperature 
maximum of the late^glacial period, the so-called „Allerød-period“. 
I had some doubts as to these peculiar marks being due to the 
operations of the beaver, but during a stay in Kristiania in 1916, 
I saw in the Zoological Museum of the University, some recent 
chips of aspen (Populus tremula) produced by the beaver biting 
through the wood and tearing off larger or smaller parts of it. Such 
a chip is shown in natural size in Fig. 5, and in both ends are 
seen the distinctly convex facets across the chip bounded by fur¬ 
rows, in the direction of which the wood will easily split. On the 
side of the chip, not seen in the figure, are found the ordinary, 
slightly concave facets. These were formed, while the chip was still 
part of the trunk or branch. From this it is clear that the ordi¬ 
nary concave facets are made by the front side of the flat convex 
incisors of the beaver, while the convex facets on the op- 
posite side of the chip are formed by the slightly ex- 
cavated inner side of the incisors, biting through and tea¬ 
ring off the chips. 
But then, how are the comparatively long branches formed? 
During a stay in Stockholm in the summer of 1923 I saw in 
the Zoological Gardens at „Skansen" a couple of live beavers. 
Swimming about in their pond they caught in their mouths long 
willow-branches Ihrown to them, and holding them in a direction 
slanting forward they snapped off the branch in two or three quick 
bites. One of the two pieces of willow branch thus formed had on its 
new terminal plane the concave facets formed by the front side 
of the teeth of the beaver, while the other piece showed the con¬ 
vex facets formed by the innerside of the incisors. By searching 
a heap of barked branches, gathered from the enclosure of the 
beavers, I saw that the convex facet were only found on the 
