The British race of Mustelaputorius, almost if not quite extinct in the English Counties away from the Welsh Marshes, and apparently nowadays equally scarce throughout Scotland, has proved remarkably successful in maintaining itself in Wales where the native stock has never quite been killed out in spite of persecution and the gin trap. The species has undoubtedly profited by the reduced intensity of game preservation since 1914 and may be said to have taken a new lease of life, and the opportunity to increase its range, in most parts of the Principality with the exception of the county of Anglesey. Occasion was taken in 1950 to obtain reports from the Forestry Commission's areas concerning the present status therein of this interesting survival among the members of our native Mustelidae, and from the resulting review of the position in the forests I am indebted to the willing co-operation of Mr A. P. Long, O.B.E., the Commissioners' Director of Forestry from Wales, and Messrs F. C. Best and W. D. Russell, Forest Conservators, and their resident Forester staffs. Polecats were formerly sufficiently numerous in most parts of Great Britain to support an active trade in their pelts. Ritchie (1920) gives records of large numbers of polecat skins offered for sale in the south of Scotland in earlier years. But the polecat falls rather an easy victim to the steel trap and it is to this fact, and the apparently incurable tendency of gamekeeping interests to destroy all carnivorous species that come within their purview, that its disappearance from the greater part of Great Britain is due. During the past two or three decades polecats have, from time to time, been reported from the island of Mull, in the Inner Hebrides, but specimens examined have been classified by zoologists as the progeny of escaped 'polecat' ferrets gone feral, or as crosses with the common ferret. Reports have also given indication that the polecat may continue to occur in parts of East Anglia and elsewhere. It is, however, only too clear that the last real stronghold of this native species is now in Wales. Specimens measured and weighed by Mr Charles Elton, M.A., of the Oxford Bureau of Animal Population, whose help and encouragement I also gratefully acknowledge, vary from 374 to 425 mm. (body length) with tail length, to the end of the bones, from 123 to 140 mm., weights varying from 830 to 1160 g. The pelage shows considerable variation in coloration, in general being yellowish to cream with dark, sometimes almost black, guard hairs on the upper parts of the body and dark hair on the face and ears, legs and feet, and on the tail. In the Tregaron district of Cardiganshire a local race has developed a distinctly rufous coloration. Formerly the polecat or foumart (in Welsh the ffwlbart) was frequently hunted with hounds. Several authorities testify that the species was still common in the first decades of the nineteenth century particularly in Wales and the Welsh border counties. Forrest (1899, p. 57) states that polecats were not rare in Shropshire in 1850 and also,