No. 2.] ON THE GUSTATORY ORGANS. 1 69 



epithelium. They are much elongated, measuring 0.04$ mm. in 

 length and 0.018 mm. in breadth. The filiform papillae follow 

 the usual type. The epiglottis was not examined. 



The Tongue of Castor fiber. 



I received a fresh specimen of this tongue. The organ 

 showed some indications of malformation, notably of the left 

 side. The hardening was conducted as in Lepiis. 



General Description. — The organ measures 74 mm. in length 

 and 25 mm. in breadth. The free portion is short, being only 

 about 18 mm. in length. The upper surface is soft and velvety 

 to the touch. Anteriorly it is flat and somewhat expanded, and 

 terminates in an obtuse apex. The fungiform papillae are of 

 fair size, and are quite numerous over the anterior fourth of the 

 dorsal surface and tip. Posteriorly they are less abundant, but 

 very conspicuous, projecting somewhat above the lingual sur- 

 face. Some of those just in front of the gustatory area are very 

 like circumvallate papillae. At the posterior part of the dorsum, 

 and well towards the base, are three papillae of the circumvallate 

 type. They form a triangle, the apex of which looks towards 

 the epiglottis. The base of the triangle is 8 mm. in length, the 

 length of the sides being 5 mm. The posterior papilla is 1 1 mm. 

 distant from the base of the organ. The lateral gustatory 

 structures are situated a trifle anterior to the triangle formed 

 by the circumvallate papillae, the left lateral organ being much 

 further forward than the right. 



Gustatory Structures. 



The Circumvallate Papillcs. — The papillae are 0.26 mm. in 

 diameter and 0.16 mm. in height. Their summits are circular 

 or slightly oval, and are more or less marked by verrucose ele- 

 vations. Superimposed on one of the papillae was one of a 

 fungiform type. This is not a very unusual occurrence ; I 

 have observed it in Lepus, and Schwalbe has called atten- 

 tion to it in Sus. A papilla thus placed does not always 

 bear bulbs, and in this instance I could not be sure of their 

 presence. The trenches encircling the papillae are wide at the 

 mouth, but narrow and uniform at their lower part. Mucous 

 and serous glands are quite abundant in this region. The 



