732 AVES. 



is totally devoid of gustatory papillae, and frequently, indeed, enveloped 

 in a horny sheath ; so that, if the sense of taste exists at all, it must be 

 to the last degree limited and obtuse. 



(2077.) In return, however, for the imperfection of the above senses, 

 the olfactory apparatus in this class of animals begins to assume far 

 greater importance than in the cold-blooded Vertebrata ; and the nasal 



Fig. 363. 



Olfactory apparatus in a Goose. 



cavity indicates, by its extent, that it is now well adapted to investigate 

 the odorous properties of the air taken in for respiration. The septum 

 narium completely divides the nose into two lateral chambers of consi- 

 derable extent, which individually communicate with the pharynx (fig. 

 363, c) ; and, upon the outer wall of each compartment, three convo- 

 luted laminaB, covered with a most delicate Schneiderian membrane, re- 

 present the turbinated bones of Mammalia, and increase the olfactory 

 surface. Of these, the middle turbinated bone (fig. 363, a) is the largest ; 

 but the superior appears to be the most important, as it is upon this that 

 the olfactory nerve is principally distributed, insomuch that Scarpa con- 

 sidered that the comparative powers of smell possessed by different birds 

 might be estimated by the development of this portion of the olfactory 

 organ. The olfactory nerves (fig. 363, 6), as in Reptiles, still enter the 

 nose without dividing, so that there is no cribriform plate to the ethmoid 

 bone. The nostrils are simple apertures, perforating some part of the 

 horny beak covering the upper mandible, and are never provided with 

 moveable cartilages or muscles, as those of Mammalia will be found 

 to be. 



(2078.) The eye of a Bird is an optical instrument of such admirable 

 construction, that, did not the nature of this work compel us to adopt 

 the strictest brevity in our descriptions, it might well tempt us to in- 

 dulge in lengthened details relative to the adaptation and uses of its 

 various parts. If we contrast the Bird with the Reptile, or more espe- 

 cially with the Fish, and consider the totally different circumstances 

 under which these animals exercise the sense of vision, we may well 

 expect extraordinary modifications in the structure of their organs of 



