1708  (1948)  Oldmixon, in his British Empire in North America, published in 1708, had this to say about the price for guns in the 1680's or thereabouts: "One with the other 10 good skins; that is Winter Beaver."
1735  (1899)  The beaver . . . was classified into eight varieties. The first was the fat winter beaver, slain in winter, which was valued at five shillings and sixpence a pound.
1944  The report [1686] . . . approves of the establishment of the standard of trade at half a pound [of Brazil tobacco] for a winter beaver.