To Lawson Tait   [13–15 March 1875]1

Your view is new to me, and has only to be suggested for its probability to be recognised.2 I presume that of course you would thus account only in part for the retention of a tail and for its modification. Your view does not preclude the conjoint use of the tail for other service, as for gliding through the air when flattened, as in the squirrel, or as a signal to beasts of prey, in accordance with Mr. Betts’s ingenious suggestion in his Nicaraguan travels, with respect to the great bushy and conspicuously-coloured tail of the skunks.3 I wish we knew the use of the extraordinary tail of the yak, which inhabits such cold regions, whether it serves solely as a fly-flapper.4 If poor Dr. Falconer5 had been alive he could have told us.

The date range is established by the relationship between this letter and the letters from Lawson Tait, 12 March [1875] and 16 March [1875].
Thomas Belt suggested that skunks did not need obscure coloration for concealment because of their ability to spray a foetid fluid at any assailant (Belt 1874a, pp. 249–50). In Descent 2d ed., p. 543, CD referred to Belt’s observation that the white bushy tail served as a conspicuous warning.
In Variation 2: 206, CD mentioned a report that Mongolians bred yaks (Bos grunniens) with white tails and sold the tails to Chinese mandarins as fly-flappers.
Hugh Falconer had sent CD his notes on yak and cattle hybrids, made on a trip to Tibet in 1837 and 1838 (see Correspondence vol. 24, Supplement, letter to Hugh Falconer, [December? 1844]). The notes were published posthumously in C. Murchison ed. 1868, 1: 581–2.

Please cite as “DCP-LETT-9885F,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-9885F