THE TEETH 



493 



posterior pillars on either side is a marked tonsillar sinus, in which an elongated, 



fusiform tonsil is situated; this is reddish in color, 



about an inch long, and is largely or completely 



concealed between two folds of mucous membrane. 



The posterior pillar is double; the upper fold passes 



to the dorsal wall of the pharynx, where it subsides; 



the lower fold goes to the side of the epiglottis. 



The tongue is wide and thin in front, thicker 

 posteriorly; it is very mobile. It is not pigmented, 

 but has a bright red color. The dorsum is marked 

 by a median groove (Sulcus medianus linguae), and 

 is thickly beset with short, pointed, filiform papilliE, 

 the free ends of which are directed backward. On 

 the root there are long conical papillae which are 

 soft, and point backward; similar papillae occur 

 on the lateral walls of the isthmus faucium. The 

 fungiform papillaj are small, and are scattered over 

 the dorsum and sides of the tongue, but are absent 

 on the posterior part of the dorsum and on the 

 root, where the conical papillae occur. There are 

 usually two or three vallate papillae on either side 

 on the posterior part of the dorsum, where the 

 conical papillae begin. Small fohate papillae are 

 also present just in front of the anterior pillars of 

 the soft palate; they are oval and are crossed by 

 about half a dozen fine fissures. In the inferior 

 part of the tip of the tongue is the lyssa, a fusiform 

 cord, composed of fibrous tissue, muscular tissue, 

 and fat. In large dogs it is about two inches (ca. 

 4 to 5 cm.) long. The lingual muscles present no 

 remarkable special characters. 



THE TEETH 



The formula of the permanent teeth is: 



/ 3 1 4 2\ 

 (l~C-P-M-) 

 V 3 1 4 3/ 



= 42 



All of the teeth have short crowns and dis- 

 tinct necks; they erupt rapidly. The crowns are 

 white, being destitute of cement.^ 



The incisors are placed almost vertically and 

 close together in the jaw bones. They do not cor- 

 respond to an opposing tooth, but rather to parts 

 of two teeth of the other jaw. They increase in 

 size from the ^first to the third. The crowns are 

 trituberculate, the central projection being the 

 largest. The labial surface is convex; the lingual 

 surface is slightly concave, and is marked off from 

 the neck by a V-shaped ridge, the cingulum. The 

 roots are narrow transversely. The lower incisors 

 are smaller than the upper ones. One or two supernumerary teeth may be present. 



The canine teeth are large, conical, and curved. The upper canine is separated 



1 Other figures which illustrate the teeth are to be found in the description of the skull. 



Fig. 434. — Tongue, Pharynx, Larynx, 

 ETC., OP Dog; Doesal View. 



The pharynx and soft palate have 

 been cut medially and reflected, and the 

 oesophagus cut off. 



1, Median groove of tongue; 2, long 

 conical papillas of root of tongue; 3, val- 

 late papillse; 4, tonsil (drawn out of ton- 

 sillar sinus; 5, floor of pharynx (promi- 

 nence here caused by cricoid cartilage 

 and m. crico-arytenoideus dorsalis) ; 7, 

 vestibule of larynx; S, epiglottis; 9, ary- 

 tenoid cartilage; 10, trachea (membran- 

 ous part) ; 11, 11, lateral lobes of thyroid 

 gland; 12, 12', anterior and posterior thy- 

 roid vessels. 



