In monkish times beaver-tail was considered to partake more of the nature of fish than flesh, and was consequently allowed to be eaten on fast days. This was, however, in the days when beavers were still abundant in all the great rivers of Europe, from most of which they have now been all but exterminated for the sake of their valuable fur, and likewise for the odoriferous secretion known as castoreum, which was formerly much used both in medicine and in perfumery. When the last beaver was killed in the British Isles is unknown, but the species still survived in Wales when the old chronicles were written; and we have testimony as to its former existence in England not only in the shape of skulls, teeth, and bones dug up from time to time in the peat of the fens and other superficial deposits, but also in place-names such as Beverley, in Yorkshire. Considerable colonies of beavers still exist, by the aid of special protection, in certain parts of Scandinavia, while a few are taken from time to time in the Rhone, but from the Rhine, and even the Vistula, they seem to have completely disappeared. In eastern Russia they probably still survive locally, as they doubtless do over a large part of Siberia, although our information on this point is very defective. Indeed the southern range of the beaver in central Asia seems to be still unknown, although it is certain that the species never existed in Kashmir or the Himalaya. Of late years it has been suggested that each of the great European river-systems possessed a special race of beavers of its own; but the evidence adduced in favour of this opinion is at present insufficient. Speaking broadly, the beaver may be regarded as a circumpolar animal; although its American representative has been separated, on account of a comparatively small difference in the shape of the bones covering the cavity of the nose, as a distinct species, under the name of _Castor canadensis_. Unfortunately, the Canadian beaver has been almost as much persecuted as its European relative, and has been exterminated from many districts. Beavers, it need scarcely be mentioned, are thoroughly aquatic rodents, which feed on vegetable substances, and have their entrances to their habitations under water. They remain active all the winter, when they swim beneath the ice. In Europe beavers have given up constructing lodges, and live in burrows. THE MARMOT (_Arctomys marmotta_) The marmot of the Alps is the typical representative of a large assemblage of burrowing rodents near akin to squirrels; the head-quarters of the group being in central Asia. By rights, of course, the name belongs exclusively to the typical species, but as it has been extended to include all the members of the group, the former is now distinguished as the Alpine marmot. Marmotte, it appears, is the Savoyard name of this rodent, which in the Engadine is designated marmotella, while its German designation is murmeltier.