DIGESTIVE SYSTEM OF BIRDS. 153 



irregular alternate series: the outer ones being the smallest, 

 which may almost be considered as a distinct row. At the pos- 

 terior part of the tongue there are two groups of smaller recum- 

 bent spines directed towards the glottis. The substance of the 

 tongue is not muscular, but is chiefly composed of an abundant 

 elastic cellular substance, permeated by an oily fat.^ Of like 

 nature is the tongue in Anserines : but the retroverted spines are 

 marginal, fig. 75, D. The tongue of the great Penguin is beset 

 with horny spines like a hedgehog's skin. 



In the Raptores the tongue is of a moderate 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 provided mth retroverted spines. In 

 the Raven it is bifid at the apex : it is more deeply cleft in the 

 ^ Nutcracker.' 



In the Struthious Birds, in many of the Waders, and in the 

 Pelecanidce, the tongue is remarkably short, as it is likewise in 

 the Kingfisher, fig. 75, c. In the Snipe it is as remarkable for its 

 length and slenderness, ib. A. In the Fieldfare (^Turdus pilaris) 

 the sheath is resolved into fine filaments at the apex of the 

 tongue, ib. b. 



In the Parrots the tongue is thick and fleshy, is terminally 

 tufted in Lories, 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. 



Muscles of tho tongue of the Fieldfare {Tardus pilaris). 



1st. The Mijlo-hyoideus: this is a thin layer of fibres attached to 

 the lower and inner border of the lower jaw, and running trans- 

 versely to a mesial tendon which separates them, and extends to 

 the urohyal. It raises the tongue towards the palate. 



2nd. The Stj/lo-hyoideus, fig. 76, «, arises from the upper and 

 back part of the lower jaw, and is inserted into the thyrohyal at 



* XXI*. 



