130 ANAT01\r5f 0^ VEKTEBRATES. 



these than in other Bh'ds. It is triturated and comminuted by 

 the mandibles, and turned about by the tongue, which here seems 

 to exercise a gustatory faculty, since indigestible parts, as the 

 coats of kernels, &c., are rejected. In the Lories the extremity of 

 the tongue is provided with numerous long and delicate papillae 

 or filaments projecting forwards. 



The marginal epithelial papillie of the tongue of the Toucan, 

 fig. 51, h, appear to test, in the way of touch, the ripeness or 

 mellowness of fruit. Similar papilla at the tip of the tongue of 

 many small birds (Humming-birds, Thrush-tribe, fig. 75, B, Field- 

 fare) exemplify probably the tactile rather than the gustatory 

 faculty. 



Fauces and tongue of the Toucan (Ramphastos). xx: 



§ 142. Organ of Smell, — The close affinity subsisting between 

 the cold and warm-blooded Ovipara is manifested in the olfactory 

 organs. The external nostrils are simple perforations, ha\dng no 

 moveable cartilages or muscles provided for dilating or con- 

 tracting their apertures, as in Mammalia. The extent of surface 

 of the pituitary membrane is not increased by any large accessory 

 cavities, but simply by the projections and folds of the turbinals. 

 The olfactory nerve passes out of the skull, as a rule, in Birds, 

 by a single foramen. The Apteryx and Dinornis form the ex- 

 ceptions. 



The external nostrils vary remarkably both in shape and posi- 

 tion, and serve on that account as zoological characters. They 

 are placed at the sides of the upper mandible in the majority of 

 Birds, but in some sjoecies are situated at or above the base of the 

 bill ; the latter is the case in the Toucans, fig. 53, d ; in the 

 Apterijx australis they are found at the extremity of the long 

 upper mandible. 



In general they are wide and freely open to facilitate the inha- 

 lation of air during the rapid motions of the bird, but they are so 

 narrow in the Herons as scarcely to admit the point of a pin ; 

 and in some Pelecanidce they are wanting, and the odorous par- 

 ticles get access to the olfactory organ from the palate. 



In the Rasores the nostrils are partially defended by a scale. 

 In the Corvidce they are protected by a iDunch of stiff feathers 



