THE PERAMELES NASUTA. 
197 
lower jaw are, in general, larger, and project more from 
their sockets than those of the upper. They are placed 
alternately with regard to those of the upper jaw, so that, 
in closing the mouth, the teeth of one jaw fall into the 
empty spaces and hollows of the other jaw; and the whole 
teeth of the lower jaw fall a little within those of the upper 
jaw. The space occupied by the teeth on both jaws, from 
the front incisor to the posterior grinder, is atbout one inch 
and eight lines. 
The upper surface of the tongue is covered with close 
and extremely minute papillae ; other papillae are seen of a 
larger size, placed at distances of nearly a line from each 
other, and appear like the ends of small bristles distributed 
over the whole tongue, and raised about the third of a line 
above its surface. On the upper surface of the roof of the 
tongue there are three large papillae, placed in a triangular 
form, on the surface of which are perceived the orifices of 
minute ducts. Each of these large papillae is enclosed in 
a distinct circular sheath, and the root of the tongue is 
fimbriated on the sides at the place where these large pa- 
pillae are situate. These three glandular papillae have the 
same form and arrangement on the tongue of the Opossum. 
On the upper surface of the tongue there is a very slight 
longitudinal groove running along the whole mesial line. 
On its lower surface there is a corresponding small ridge 
running in the same direction, and extending from the 
point to the frsenum. There is a small fold of the skin on 
each side of the mesial ridge on the lower surface, which is 
raised about a line from the surface, and extends in the 
same direction, from the apex to the frasnum. Below the 
tongue, on the floor of the mouth, there are likewise two 
longitudinal folds, corresponding in size and position witli 
those on the lower surface of the tongue, and having a 
small longitudinal groove in the middle between them. 
