158 FREDERICK TUCKERMAN. 



tributed to the anterior third, and are much smaller than those 

 of the middle portion. 



On each lateral half of the tongue is situated, near the ante- 

 rior margin of the posterior third of the papillary surface, a 

 large circumvallate papilla. These two papillae lie in the same 

 plane, and are 6 mm. apart. The left one is a little the larger 

 of the pair. They are elliptical in form, and are placed at 

 an oblique angle to the long axis of the tongue, with their 

 anterior extremity directed outwards. Each papilla is en- 

 circled by a deep and rather wide trench, in which it is quite 

 movable. Around the trench, and also forming part of its 

 wall, are large conical- shaped papillae. The larger of the two 

 circumvallate papillae measures, at its summit, 2 mm. in its 

 long diameter, and 1*4 mm. in its short. The upper surfaces 

 of both present an uneven or ridged appearance. No papilla 

 foliata was found. 



The under surface of the tongue is perfectly smooth except 

 at the borders and tip, at which points are distributed nume- 

 rous small tactile or mechanical papillae. Anteriorly it is 

 marked by a deep median groove, commencing at the fraenum 

 and running towards the apex. This becomes, however, rapidly 

 superficial, and disappears altogether about 9*5 mm. from 

 the tip. 



The Circumvallate Papillae. — These papillae are dis- 

 tinctly lobate posteriorly ; their upper and lateral contours 

 are necessarily, therefore, somewhat uneven and irregular. 

 Still, in some sections, I found the sides comparatively symme- 

 trical. The diameter of the papilla at its base is always less 

 than at the summit. In many sections the sides are vertical, 

 or slightly oblique for about half their length, and then bend 

 inwards and downwards. 



The relation of the trench to the shape of the papilla is 

 peculiar and, so far as I am aware, quite unusual (see figs. 2 

 and 3). Posteriorly, it is wide and deep, and passes directly 

 beneath the papilla, thus giving it (the papilla), for about half 

 its diameter, a free under surface. 



Anteriorly and externally the trench becomes narrower 



