1 8 Btdletin of the Natural History Society. 
At the horizon of No. 8 the molluscs of the lake were found in 
the greatest abundance. They were entangled among the twigs and 
branches which abounded on the slope of the dam and include, 
beside the genera mentioned above, a water-snail of the genus 
Physa. 
The remains of the molluscs bcome quite scarce in the next divi- 
sion (No. 9) along the face of the dam, having been driven further 
out into the lake by the accumulation of vegetable rubbish and de- 
bris brought in by the beavers. But though fragments of the 
branches of trees are quite plentiful in this part of the dam, the 
layers are more sandy, and the specific gravity greater than that of 
the underlying portions of the dam. This may have been owing either 
to increased floods in the streamlet which here enters the lake, or to 
the operations of the beavers in plastering the dam. The specific 
gravity here is 1.4, but in the lower layers, (No. 6) in the front 
slope of the dam is 1.08. In the foot and a half in depth of black 
loam which forms the top of the dam the specific gravity was only 
0.24. This portion was a})parently the part of the dam which stood 
out of the water, was not permeated by miid, and became the 
foundation for a vigorous growth of trees when the beavers were 
driven from the lake. 
About the slopes and ends of the dam grew the grasses, sedges, 
horsetails and other herbaceous plants which have shed their seed so 
plentifully into the lake, in its front ; and on the other side of the 
dam was a small pond fed by a little rivulet (the only one which 
enters Lawlor’s Lake) — where, no doubt, the habitations of these 
intelligent creatures were built. 
TRACES OF PRIMEVAL MAN. 
Such was the home the beavers had made for themselves in this 
secluded valley, providing for their own wants and at the same time 
piotecting the interests of their molluscan neighbors in the lake. 
It is to be feared, however, that their busy and peaceful home was 
not free from the incursions of enemies. A small fragment of char- 
coal found some distance beneath the surface in the deposits of the 
Southern Basin tells, probably, of the presence of Man in this valley, 
long before the advent of the English or the French Colonist, — 
possibly even before the arrival of the “ Indian ” race, whom the 
