TONGUE AND GUSTATORY ORGANS OF MEPHITIS MEPHITIOA. 1 57 



dening was completed. Subsequently portions of the organ 

 were embedded in celloidin in the usual manner. My efforts 

 to obtain sections stained with chloride of gold were not 

 successful. 



General Description of the Tongue. — The organ is 

 44 mm. long, 19 mm. wide, and 9 mm. in thickness. It is per- 

 fectly free for 15 mm. from the fraenum, or a trifle more than 

 one third of its length. Its length is therefore a little more 

 than twice its width, which is quite uniform from the base to 

 near the apex. Here it becomes thinner and somewhat ellip- 

 tical in form. The upper surface is slightly convex posteriorly, 

 and more or less flattened near the anterior extremity. There 

 is a very slight raphe running forwards from the middle third 

 of the tongue to its junction with the anterior third; here it 

 takes the form of a shallow groove, which disappears just before 

 reaching the tip. There is also a well-defined mesial groove 

 at the posterior part of the dorsum, commencing midway 

 between the two circumvallate papillae, and running backwards 

 for 10 mm. In the anterior third, beginning a little back 

 from the apex, and reaching to the lateral margin, are four or 

 five transverse ridges with corresponding depressions curving 

 backwards, which give to this part of the tongue a corrugated 

 appearance. 



The upper surface, including the lateral margins in front of 

 and lying between the circumvallate papillae, is covered with 

 tactile and mechanical papillae, the points of which are directed 

 backwards. These become gradually smaller as they approach 

 the anterior extremity. The region of the tongue lying behind 

 the gustatory area has projecting from its surface large cone- 

 shaped papillae, the apices of which are directed backwards and 

 inwards. These increase in size, but decrease in number, as 

 they recede towards the posterior limits of the organ. 



Papillae of the fungiform type are scattered quite uniformly 

 over the dorsum and upon the sides of the middle third of the 

 tongue, but terminate posteriorly in front of the area of the 

 circumvallate papillae. The average distance between them in 

 this region is about 05 mm. They are very sparingly dis- 



