Tuckerman — Gustatory Origans of Lepus Amerioanus. 277 



Art. XXXIX — On the Gustatory Organs of the American 

 Hare, Lepus Amerioanus ; by Frederick Tuckerman. 



General description of the tongue. 



The tongue of this rodent shows two well-marked divisions, 

 a more or less flattened and expanded anterior portion, and a 

 raised posterior part. The posterior division is the longer of 

 the two by about one-fifth, the total length of the organ being 



The anterior division is 13*5 mm in breadth, 5 to 8 mm in thick- 

 ness, and is free from the floor of the mouth for 15 mm . The 

 upper surface and lateral borders of this division are covered 

 with small, closely set, cone-shaped papillae, the apices of 

 which are directed backward. The epithelium covering the 

 papillae is dense and imbricated, and in their upper half either 

 partly or wholly cornified. They measure about O20 mm in 

 height, and terminate in one or more minute spines. There is 

 only the faintest trace of a mesial furrow on the papillate sur- 

 face, but the organ is impressed transversely, corresponding to 

 the palatal grooves. The apex is short, broad and obtuse. The 

 under surface is smooth, and marked by a longitudinal median 

 ridge extending from the tip of the tongue to the fraenum. 

 Papillae of the fungiform type are not especially numerous. 

 They are rather thinly distributed over the anterior dorsal sur- 

 face, and the posterior division of the organ appears to be 

 nearly devoid of them. They are however quite thickly set 

 about the tip, particularly its inferior part, and they are also 

 collected into a single line on each side of the tongue, from 

 the apex to the anterior limits of the foliate organs. 



The posterior division, which rises somewhat abruptly above 

 the level of the preceding, is ll'5 mm in breadth and 8 to 12 mm 

 in thickness. Anteriorly, the lateral margins of this division 

 are stained a rusty-brown color. In some specimens this pig- 

 mentation of the epithelium involves nearly the whole of the 

 anterior surface of the division. The upper surface is slightly 

 convex, and, in front of the circumvallate area, is covered with 

 closely-set mechanical papillae, the points of which are directed 

 backward. The extreme posterior region is traversed by a 

 few inconspicuous ridges, in the furrows between which may 

 be seen (with the aid of a lens) the minute orifices of the mu- 

 cous ducts which open on the free surface in this region. The 

 circumvallate papillae are usually two in number. They are 

 placed one on either side of the median line, 3'6 mm apart, and 

 10 mm from the base of the organ. Very rarely there are three 

 papillae of this type present. When this is the case, they are 



