272 THE ZOOLOGIST. 
the marvellous stories told of its intelligence and sagacity by the 
older writers. They are often of great length—sometimes 150 
or 200 yards and more—and run across the course of the brook 
inhabited by the Beavers,—sometimes in a straight line, some- 
times in a curved form, according to peculiarities in the ground 
or the stream, and the exigencies of the engineers. They are 
composed, like the “‘lodges,” of lengths cut from the trunks and 
branches of trees, filled in with smaller sticks, roots, grasses, 
and moss, and all plastered with mud and clay in a most 
workmanlike manner, until the whole structure becomes quite 
water-tight. Their height is from six to ten feet, and their 
thickness at the bottom sometimes as much as double this, but 
diminishing upwards by the slope of the sides until the top is 
only from three to five feet wide. These dams convert even 
small rivulets into large pools of water, often many acres in 
extent ; and in districts where Beavers abound these pools may 
occupy nearly the whole course of a stream, one above the other, 
almost to its source. Their use to the Beavers, as constantly 
furnishing them with a sufficiency of water in which to carry on 
their business, and especially to float to their ‘‘lodges”’ the tree- 
trunks necessary for their subsistence, is easily understood ; 
but it is a more remarkable circumstance that by this means 
the Beavers exercise a considerable influence upon the external 
appearance of the locality inhabited by them, which may persist 
even long after they have themselves disappeared. In and about 
the pools the constant attacks of the Beavers upon the trees 
produce clearings in the forest, often many acres in extent: at 
the margins of the pools the formation of peat commences, and 
under favourable circumstances proceeds until the greater part 
of the cleared space becomes converted into a peat-moss. These 
peaty clearings are known as ‘‘ Beaver-meadows,” and they 
have been detected in various countries where this animal is 
now extinct. 
That the Beaver once existed in the British Islands, even 
within historic times, is a fact which renders it all the more 
interesting to us. It is mentioned in the Welsh Laws made by 
Howel Dha (a.p. 940), where the value of its skin is fixed at 
120 pence, the skin of a Marten being at that date only 
24 pence, and that of a Wolf, Fox, and Otter 8 pence. 
Giraldus Cambrensis, in his description of his journey 
