[286] The young of _Ardea rufescens_ and _A. cærulea_ of the U. States are likewise white, the adults being coloured in accordance with their specific names. Audubon (‘Ornith. Biography,’ vol. iii. p. 416; vol. iv. p. 58) seems rather pleased at the thought that this remarkable change of plumage will greatly “disconcert the systematists.” [287] I am greatly indebted to the kindness of Mr. Sclater for having looked over these four chapters on birds, and the two following ones on mammals. By this means I have been saved from making mistakes about the names of the species, and from giving any facts which are actually known to this distinguished naturalist to be erroneous. But of course he is not at all answerable for the accuracy of the statements quoted by me from various authorities. [288] See Waterton’s account of two hares fighting, ‘Zoologist,’ vol. i. 1843, p. 211. On moles, Bell, ‘Hist. of British Quadrupeds,’ 1st edit. p. 100. On squirrels, Audubon and Bachman, ‘Viviparous Quadrupeds of N. America,’ 1846, p. 269. On beavers, Mr. A. H. Green, in ‘Journal of Lin. Soc. Zoolog.’ vol. x. 1869, p. 362. [289] On the battles of seals, see Capt. C. Abbott in ‘Proc. Zool. Soc.’ 1868, p. 191; also Mr. R. Brown, ibid. 1869, p. 436; also L. Lloyd, ‘Game Birds of Sweden,’ 1867, p. 412; also Pennant. On the sperm-whale, see Mr. J. H. Thompson, in ‘Proc. Zool. Soc.’ 1867, p. 246. [290] See Scrope (‘Art of Deer-stalking,’ p. 17) on the locking of the horns with the Cervus elephas. Richardson, in ‘Fauna Bor. Americana,’ 1829, p. 252, says that the wapiti, moose, and reindeer have been found thus locked together. Sir A. Smith found at the Cape of Good Hope the skeletons of two gnus in the same condition. [291] Mr. Lamont (‘Seasons with the Sea-Horses,’ 1861, p. 143) says that a good tusk of the male walrus weighs 4 pounds, and is longer than that of the female, which weighs about 3 pounds. The males are described as fighting ferociously. On the occasional absence of the tusks in the female, see Mr. R. Brown, ‘Proc. Zool. Soc.’ 1868, p. 429. [292] Owen, ‘Anatomy of Vertebrates,’ vol. iii. p. 283. [293] Mr. R. Brown, in ‘Proc. Zool. Soc.’ 1869, p. 553. [294] Owen on the Cachalot and Ornithorhynchus, ibid. vol. iii. p. 638, 641. [295] On the structure and shedding of the horns of the reindeer, Hoffberg, ‘Amœnitates Acad.’ vol. iv. 1788, p. 149. See Richardson, ‘Fauna Bor. Americana,’ p. 241, in regard to the American variety or species; also Major W. Ross King, ‘The Sportsman in Canada,’ 1866, p. 80.