But it is, above all, the Beaver (_Castor fiber_) who exhibits the highest qualities as an engineer and mason. This industrious and sagacious Rodent is well adapted to inconvenience the partisans of instinct as an entity, apart from intelligence, which renders animals similar to machines and impels them to effect associated acts, without themselves being able to understand them, and with a fatality and determination from which they can under no circumstance escape. Beavers now only live in Canada. A few individuals may, however, still be found on the banks of the lower Rhone, in Camargue, and on a few other European rivers. Several centuries ago they existed in the neighbourhood of Paris in considerable numbers. The Bievre gained its name from the old French word for Beaver, and its resemblance to the English name, as well as to the German (_Biber_), is striking. In the sixteenth century, according to Bishop Magnus of Upsala, the Beaver was still common on the banks of the Rhine, the Danube, and on the shores of the Black Sea, and in the North it still exercised great art in its constructions. In the twelfth century it was found in Scotland and Wales. If we go back to ancient times, we find that Herodotus mentions that the Budini who lived in the neighbourhood of the Black Sea used the skins of the Beavers, which abounded there, on the borders of their garments; and in the time of Pliny the Beaver was so common there that he speaks of it as the Pontic Beaver. Fossil remains of the Beaver have also been found throughout Europe in conjunction with those of the Mammoth and other extinct animals. But the civilisation of the Beaver has perished in the presence of Man's civilisation, or rather of his persecution. In regions where it is tracked and disturbed by Man the Beaver lives in couples, and is content to hollow out a burrow like the Otter's, instead of showing its consummate art. It merely vegetates, fleeing from enemies who are too strong for it, and depriving itself of a dangerous comfort. But when the security of solitude permits these animals to unite in societies, and to possess, without too much fear, a pond or a stream, they then exhibit all their industry. They build very well arranged dwellings, although at first sight they look like mere piles of twigs, branches, and logs, heaped in disorder on a small dome of mud. At the edge of a pond each raises his own lodge, and there is no work by the colony in common. If, however, there is a question of inhabiting the bank of a shallow stream, certain preliminary works become necessary. The rodents establish a dam, so that they may possess a large sheet of water which may be of fair depth, and above all constant, not at the mercy of the rise and fall of the stream. A sudden and excessive flood is the one danger likely to prove fatal to these dykes; but even our own constructions are threatened under such circumstances.