382 CONTRIBUTIONS TO VETERINARY PATHOLOGY. 
The frontal sinus contained an accumulation of inspissated pus; 
the septum nasi was of a leaden hue, as also the membrane cover- 
ing the turbinated bones, which was much inflamed and thickened, 
but there was no appearance of ulceration. 
The difficulty was, to ascertain how the food got there. By the 
most careful search, it was very evident that it could not have 
been passed up through the external nostril ; we therefore pro- 
ceeded gradually to dislodge the accumulated food and matter, 
searching for its entrance, and at last found a hole sufficiently large 
to admit the little finger in the alveolar space appertaining to the 
last molar tooth, the fang of which was completely gone, and only 
a small portion of the crown remaining. 
It was apparent, therefore, that the food, during mastication, was 
continually being forced into the space it occupied. The fourth 
molar tooth was absent, having evidently been lost from previous 
disease. 
Upon examining the right side of the head, we found the 
turbinated bones and membranes covering the septum nasi com- 
paratively healthy ; but on looking into the maxillary sinus we 
found a cyst, about the size of a large walnut, containing limpid 
fluid, occupying the space immediately above the fang of the 
fourth molar tooth ; and on examining this tooth we found it much 
decayed and quite loose, and below the level of the other molar 
teeth. 
The teeth of the lower jaw appeared healthy. 
Wishing to send you the head, we thought it better not to pro- 
ceed in the examination, else we should have carried our investi- 
gation further, which would have prevented you from having a 
fair view of the diseased parts. 
*** The mare — that being the sex according to the mouth — we 
should take by her teeth to have been about twenty years of age. 
Her incisors are all sound, and fairly worn ; and so are the molars 
of the under jaw. But of the upper jaw, the near side second, fourth, 
and sixth, and the off side fourth molar teeth, are in a state of pro- 
gressive decay : the worst being the near fourth and sixth, and 
the off fourth. The near fourth, indeed, has disappeared some 
time ago, as would appear from its alveolus being completely filled 
up, covered with gum, and obliterated, save a small portion of the 
tooth remaining anteriorly. The near sixth is also almost wanting; 
its middle and fangs being totally rotted away. Two- thirds of the 
off fourth are gone, and two portions that remain are loose, and 
ready to fall out. 
The vacuity caused by the defective last molar teeth of the near 
side has opened a passage into the autrum or maxillary sinus, 
