1877.] Concerning Foot-Prints. 411 
at Beauharnois, Canada, situated about twenty miles westward 
of Montreal. These foot-prints were made a subject of study 
by Professor Owen, and were considered by him as having been 
formed by a large crustacean, resembling very closely in structure 
the Limulus, or “king-crab,”’ socommon along the Atlantic coast 
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Wie ans, 
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(Fie. 77.) PROTICHNITES SEPTEM- ; 
NOTATUS, 0. Porspam. (Fie. 78) CLIMACTICHNITES. Porspam. 
at the present day. The tracks consist of a medial furrow, ac- 
companied on both sides by a large number of small indentations. 
The entire series of impressions is about six inches wide, and 
has been followed in some cases for several feet. It will be no- 
ticed that the tracks on each side of the medial line have a defi- 
nite rotation and form separate groups which regularly succeed 
one another, —each of these sets of impressions in the trail repre- 
sented above being formed by seven individual tracks on each 
side of the furrow. From the nature of the impressions and the 
regularity with which they succeed each other, we conclude that 
they were made by an animal having either seven individual legs 
on each side of the body, or else a fewer number of limbs which 
were divided at their extremities ; the latter theory is the one 
that Professor Owen considered most probable. The modern 
Limulus, whose trail resembles these ancient foot-prints almost 
exactly, has five pairs of true legs, four of which are forked at 
their extremities, while the hindmost pair is terminated by four 
lamellar appendages. The rigid tail of the Limulus leaves a fur- 
Tow on the sand over which the animal walks corresponding to 
the central furrow in the trails on the Potsdam sandstone. That 
this ancient furrow was also made by a rigid tail, and not by the 
under surface of the animal’s body, is shown by the fact that when 
a sharp curve was followed, the medial furrow swept to one side 
and sometimes obliterated the foot-prints on the convex side of 
the trail. : | 
Several series of foot-prints of the same general nature as 
