_a_, Parotid gland; _a′_, _a″_, cervical and submaxillary angles of
_a_; _b_, _c_, ventral and dorsal buccal glands; _d_, labial glands;
_e_, masseter muscle; _f_, _f′_, lymph glands; _g_, dotted line
indicating outline of submaxillary gland, which is concealed.
(Ellenberger-Baum, Anat. d. Haustiere.)
]
The average periods of =eruption= of the teeth are given in the
subjoined table.
TOOTH│ ERUPTION │ CHANGE
│ │
I_{1}│2 to 4 weeks │12 months
I_{2}│upper 2 to 3 months│
│lower 1½ to 2 month│16 to 20 months
I_{3}│Before birth │8 to 10 months
C │Before birth │9 to 10 months
P_{1}│5 months │
─────┼───────────────────┼───────────────────
P_{2}│5 to 7 weeks │12 to 15 months
P_{3}│upper 4 to 8 days │ „
│lower 2 to 4 weeks.│
P_{4}│upper 4 to 8 days │ „
│lower 2 to 4 weeks │
─────┼───────────────────┼───────────────────
M_{1}│4 to 6 months │
M_{2}│8 to 12 months │
M_{3}│18 to 20 months │
The =cheek teeth= increase in size from before backward. They have (with
certain exceptions noted below) complex tuberculate crowns; the term
bunodont is applied to this condition, as distinguished from the
selenodont structure in horses and cattle, in which there are prominent
ridges of enamel. They are short-crowned teeth with a distinct neck and
root. The first tooth in each jaw is small, simple, and appears only
once; in the lower jaw it is near the canine, in the upper near the
second cheek tooth. The next two teeth are larger, laterally compressed,
and sectorial. The fourth tooth below is larger, but otherwise like the
preceding ones, while the upper one is much wider and is tuberculate.
[Illustration: