m the maxillary process are
developed the cheeks, certain of the facial bones, the lateral
portions of the upper lip, the soft and hard palate (with the
exception of the os incisivum). The development of the face is
completed about the end of the second month of intra-uterine life.

HARE-LIP AND CLEFT PALATE

Hare-lip is a congenital notch or fissure in the substance of the
upper lip, and cleft palate a congenital defect in the roof of the
mouth. Either of these conditions may exist alone, but they occur so
frequently in combination that it is convenient to consider them
together.

In hare-lip the cleft may be median or lateral, and it may or may not
be associated with a cleft in the palate. The resemblance to the
Y-shaped cleft in the upper lip of the hare, suggested by the name, is
in most cases only superficial.

#Median hare-lip# is extremely rare. It occurs in two forms: one in
which there is a simple cleft in the middle of the lip, the result of
non-union of the two globular processes; another in which there is a
wide gap due to entire absence of the parts developed from the mesial
nasal process--the central portion of the lip, the mesial segment of
the os incisivum, and the septum of the nose. The second form is
usually associated with cleft palate.

#Lateral hare-lip# is much more common. It is due to imperfect fusion
of the globular process with the labial plates of the maxillary
process. There may be a cleft only on one side of the lip, or the
condition may be bilateral. In some cases the cleft merely extends
into the soft parts of the lip--_simple hare-lip_ (Fig. 232) forming a
notch with rounded margins on which the red edge of the lip shows
almost to the apex. In other cases the cleft passes into the alveolus
of the jaw--_alveolar hare-lip_--partly or completely separating the
mesial and lateral segments of the premaxillary bone (Fig. 233). These
cases are usually combined with cleft palate (Fig. 236).

[Illustration: FIG. 232.--Simple Hare-lip.]

[Illustration: FIG. 233.--Unilateral Hare-lip with Cleft Alveolus.]

When the hare-lip is _bilateral_, the two clefts may be unequal, one
forming a simple notch in the lip, the other passing into the nostril.
In most cases, however, both clefts are complete, and the mesial
portion of the lip is entirely separated from the lateral portions.
The central portion or prolabium is usually smaller than normal, and
is closely adherent to the os incisivum. This