AVES. 

 Fig. 151, 



315 



In the Humming-bird, and especially in 

 the Toucan and Woodpecker, the horny sheath 

 of the glosso-hyal presents singular pecu- 

 liarities. In the Humming-bird it is divided 

 at its extremity into a pencil of fine hairs, 

 well fitted for imbibing the nectar and farina 

 of flowers. In the Toucan's tongue (fig. 152) 

 the sheath gives off from the lateral margins 

 stiff bristle-like processes which project for- 

 wards ; this structure is continued to the apex, 



c- 



SS 



Os hyoides and larynx 



Swan. 



Fig. 152. 



and the tongue so provided becomes an in- 

 strument for testing the softness and ripe- 

 ness of fruit, and the fitness of other objects 

 for food, thereby acting as a kind of antenna 

 or feeler. A similar but less developed struc- 

 ture is found in the tongue of the frugivorous 

 Touraco. 



In the Woodpeckers the apex of the 

 horny sheath (a, Jig. 153, 154) gives off at, the 

 sides short-pointed processes directed back- 

 wards, which thus convert it into a barbed 

 instrument, fitted for holding fast the insects 

 which its sharp point has transfixed, after the 

 strong beak has dislodged them from their 

 hiding places. The cornua of the os hyoides 

 in the Woodpecker extend backwards to the 

 vertebral column, wind round the back of the 

 head, and converge as they pass forwards to be 

 inserted in a canal generally on the right side of 

 the upper mandible (rf, e, fg. 153, 154.) 



Fig. 153. 



Cranium and tongue of a Woodpecker. 



One of the most remarkable structures which 

 the tongue presents in this class is met with in 

 the Flamingo, where it is remarkable both for its 

 size, texture, and singular armature. The tongue 

 is almost cylindrical, slightly flattened above, 

 and obliquely truncate anteriorly, so as to cor- 

 respond with the form of the inferior mandible. 

 The pointed extremity of the truncated part is 

 supported beneath by a small horny plate. 

 Along the middle of the upper surface* there is 

 a moderately deep and wide longitudinal 

 furrow; on either side of which there are 

 from twenty to twenty-five recurved spines, 

 from one to three lines in length. These 

 spines are arranged in an irregular alternate 

 series : the outer ones being the smallest, which 



Tongue of the Toucan. 



may almost be considered as a distinct row. 

 At the posterior part of the tongue there are 

 two groups of smaller recumbent spines di- 

 rected towards the glottis. The substance of 

 the tongue is not muscular, but is chiefly 

 composed of an abundant elastic cellular sub- 

 stance, permeated by an oily fat. 



In the Raptorcs the tongue is of a mode- 

 rate length, broad, and somewhat thick, and 

 has a slight division at the tip. In the Vultures 

 its sides can be voluntarily approximated so 

 as to form a canal, and its margins are pro- 

 vided with retroverted spines. In the Ilaven 

 it is bifid at the apex. 



In the Struthious birds, in many of the 

 Waders, and in the Pelecanida, the tongue is 

 remarkably short. 



In the Parrots it is thick and fleshy, serves 

 admirably to keep steady the nut or seed upon 

 which the strength of the mandibles is exerted, 

 and is applied to the kernel so extracted, as if 

 to ascertain its sapid qualities. 



The following are the muscles of the tongue 

 in birds. 



1st. The Genio-hyoideus of Vicq d'Azyr, 

 or the Mylo-hyoideus according to Cuvier. 

 This is a thin layer of fibres attached to the 

 lower and inner border of the lower jaw, and 

 running transversely to a mesial tendon which 

 separates them, and extends to the uro-hyal. 

 It raises the tongue towards the palate. 



2d. The Stylo-hyoideus arises from the upper 

 and back part of the lower jaw, and divides into 

 three or more portions : the posterior descends 

 obliquely forwards, and is inserted into the 

 tendinous commissure of the preceding mus- 

 cle; the middle portion is inserted into the 

 1 uro-hyal :' the anterior fasciculus is inserted 

 into the side of the basi-hyal above the trans- 

 verse hyo-glossus. The actions of these dif- 

 ferent portions vary according to their insertion ; 

 the first and second depress the apex of the 

 tongue by raising its posterior appendage, 

 (uro-hyal,) the third raises the tongue and 

 os hyoides, and draws it to one side when it 

 acts singly. 



3d. The Genio-hyoideus arises by two fleshy 



