Chap. XIII. Decoration. 383 



at the commencement of this chapter, are wonderfully diver- 

 sified. The plumes on the front or back of the head consist of 

 variously-shaped feathers, sometimes capable of erection or 

 expansion, by which their beautiful colours are fully displayed. 

 Elegant ear-tufts (see fig. 39, ante) are occasionally present. 

 The head is sometimes covered with velvety down, as with the 

 pheasant ; or is naked and vividly coloured. The throat, also, is 

 sometimes ornamented with a beard, wattles, or caruncles. Such 

 appendages are generally brightly-coloured, and no doubt servo 

 as ornaments, though not always ornamental in our eyes; for 

 whilst the male is in the act of courting the female, they often 

 swell and assume vivid tints, as in the male turkey. At such 

 times the fleshy appendages about the head of the male Tragopan 

 pheasant (Ceriomis Temminckii) swell into a large lappet on the 

 throat and into two horns, one on each side of the splendid 

 top-knot ; and these are then coloured of the most intense blue 

 which I have ever beheld. 62 The African hornbill {Bucorax 

 abyssinkus) inflates the scarlet bladder-like wattle on its neck, 

 and with its wings drooping and tail expanded " makes quite a 

 " grand appearance." 63 Even the iris of the eye is sometimes 

 more brightly-coloured in the male than in the female; and this 

 is frequently the case with the beak, for instance, in our common 

 blackbird. In Buceros comtgatus, the whole beak and immense 

 casque are coloured more conspicuously in the male than in the 

 female ; and " the oblique grooves upon the sides of the lower 

 " mandible are peculiar to the male sex." 64 



The head, again, often supports fleshy appendages, filaments, 

 and solid protuberances. These, if not common to both sexes, 

 are always confined to the males. The solid protuberances have 

 been described in detail by Dr. W. Marshall, 05 who shews that 

 they are formed either of cancellated bone coated with skin, or 

 of dermal and other tissues. With mammals true horns are 

 always supported on the frontal bones, but with birds various 

 bones have been modified for this purpose ; and in species of the 

 same group the protuberances may have cores of bone, or be 

 quite destitute of them, with intermediate gradations connecting 

 these two extremes. Hence, as Dr. Marshall justly remarks, 

 variations of the most different kinds have served for the 

 development through sexual selection of these ornamental 

 appendages. Elongated feathers or plumes spring from almost 



62 See Dr. Murie's account with 64 'Land and Water,' 1868, p. 



coloured figures in ' Proc. Zoolog. 217. 



Soc' 1872, p. 730. 65 'Ueberdie Schadelhbeker,' &c, 



68 Mr. Monteiro, ' Ibis,' vol. iv. ' Niederlandischen Archiv fur Zoo* 



1862, p. 339. logie,' 13. 1. Heft. 2, 1872. 



