﻿30 ON THE CLASSIFICATION OF BIRDS. 



they are, nevertheless, solid, and proceed from the front 

 of the head. This process in the cassowary, is repre- 

 sented in a most remakable way in the rhinoceros ; 

 and if the circles of the groups which contain these 

 animals are compared, it will be found that they mu- 

 tually represent each other. The other naked append- 

 ages found on the heads of birds, are always fleshy, 

 and are attached either to the front of the head, as 

 in the turkey, or on the sides of the mouth, as in the 

 cock. Rasorial types, more than any other, furnish 

 us with these unusual deviations from the ordinary ap- 

 pearance of birds : several examples, however, occur 

 in the grallatorial form, as in the genus Casmorhyn- 

 chus among the chatterers or fruit-eaters, the Psariance, 

 the Ceblepyrus lobatus, the aberrant forms of the Cha- 

 radriadce, and the different grallatorial sub-genera of 

 the Muscicapidce ; none of which, by the most minute 

 analysis, can be reduced to rasorial types. There is a 

 peculiarity, nevertheless, among these, which deserves 

 notice ; for the greater part possess only a naked skin 

 round the eye, similar to that in the genus Perspicilla 

 (fig» 11.) among the water chats. The only natatorial 

 birds we can recollect as 

 having naked appendages, 

 are the lobed duck of New 

 Holland and the common 

 Muscovy duck : there is 

 one example in the tenui- 

 rostral tribe, and none in 

 the fissirostral. 

 (39.) Crests are the most beautiful appendages to the 

 heads of birds ; and give to those, which are even of the 

 plainest colours, an imposing and attractive appearance. 

 The use of the crest is twofold : in most birds so distin- 

 guished, it is chiefly an ornament, given as a mark of 

 distinction, almost exclusively, to the male ; in others, it 

 not only is ornamental, but useful as a sort of defence. 

 To explain this novel assertion, we can safely say that 

 many are the beautiful crested woodpeckers of the 



