54 INTRODUCTION. 



pointed papillae ; at its anterior extremity is a soft prominence, 

 from which proceeds forwards a soft ridge, f. The tip or horny 

 part is slightly, the lower mandible deeply, concave. The 

 small conical papillae are not glandular, but prominences 

 sheathed with a substance of a horny or cuticular nature, al- 

 though generally soft. 



The tongue, Fig. 3, is short, fleshy at the base, rather nar- 

 row, concave above ; its sides nearly parallel ; the tip, «, 

 rounded, its free part beneath. Fig. 4, a, sheathed with a 

 horny substance ; the lower surface of the sides toward the 

 base furnished with large crypts, secreting a fluid analogous to 

 saliva, but viscid ; the base, ^, concave in its outline, and 

 fringed with pointed papillae directed backwards. The space 

 between the base of the tongue, 6, and the aperture of the 

 windpipe, <?, is covered with mucous crj^ts, of which there are 

 also lateral series, <^, d ; and the posterior part of the pharynx, 

 €., is supplied w^ith similar bodies irregularly disposed. The 

 aperture of the glottis, c, is defended by the papillar base of 

 the tongue ; and behind it are two flaps, /, /, covered with pa- 

 pillae, directed backwards. 



Fig. 4. represents, besides the alimentary canal, «, the 

 tongue ; 5, ^, the hyoid bones ; c, d, the trachea or windpipe, 

 composed of numerous narrow rings, and dividing at the lower 

 part of the neck into two bronchi, ^, which open into the 

 lungs ; /, the heart, of which the right side, g^ has been laid 

 bare, while the left, /^, is covered with the pericardium ; /, j, 

 the rio-ht and left lobes of the liver. The heart and liver cover 

 the lower part of tlie oesophagus, a portion of the stomach, and 

 the lungs. The oesophagus, 6, c?, measured from the base of the 

 tonofue to the stomach is six and a half inches long. At the very 

 commencement, where its diameter is nearly an inch, it begins 

 to enlarge, and continues rapidly widening, so as about the 

 middle of the neck to form a crop, h, capable of being distended 

 to a diameter of nearly two inches, and lying towards the right 

 side, the trachea, c, d, passing along the left, or rather running 

 straight down the neck. 



Fig. 5. represents the continuation of the oesophagus, and the 

 rest of the alimentary canal. On entering the thorax at /, the 



