INTRODUCTION. Xvii 



arch ; and there are two or three pairs of bony or cartila- 

 ginous plates, by which the pituitary membrane is extended. 

 The nasal fossae are concealed within the base of the bill, 

 but have no sinuses. The external opening varies greatly 

 in size, form, and in the degree in which it is covered by 

 membrane, hairs, or feathers ; but the relation between 

 the degree of nudity, or otherwise, of the nostrils, and the 

 delicacy of the sense of smell, is by no means evident. 

 The great power of smell supposed to exist in Vultures 

 has certainly been greatly exaggerated. Waders have 

 probably this sense most developed, and Gallinaceous 

 birds the least. 



Taste is but little developed in most birds, the bill 

 being thin and horny, and most birds swallow their food 

 without masticating it. In Parrots and Ducks the tongue 

 is thick and fleshy, and there is no doubt that these birds 

 have the sense of taste, and do distinguish and select their 

 food accordingly. In some, with the usual horny tongue, 

 the tip is entire ; in others it is more or less bifid ; and in 

 some it is provided with a brush of hairs, which enables 

 them to sip the honey, and brush off the pollen of flowers. 

 In others, again, it is long "and tubular, and in some it is 

 provided with a barbed end, or spear, to secure insects. 

 The hyoid bone is greatly developed in Wood-peckers, pass- 

 ing over the whole extent of the cranium, and, by a peculiar 

 apparatus, enabling the tongue to be protruded to a great 

 length. This is simply the attachment of certain muscles 

 from the lower jaw to the posterior part of the crura of 

 the hyoid bone, the contraction of which pulls down the 

 bone, and thus forces out the tongue. 



The sense of touch or feeling is but little developed, 

 except perhaps in the bill of Ducks, and of some Gralla- 

 tores, especially of Snipe and their allies. 



