The Lips.—The European type of lips is well known both as regards their proportions and their lines of contour which determine the distinctive form.
Sometimes this graceful modeling is wanting; the contour of the lips is formed of almost horizontal lines, the oral aperture is very wide, and has the appearance, especially when laughing, of being edged by a perfectly uniform, narrow line, thus resembling the mouth of a monkey.
At other times we meet with thick, fleshy lips, slightly pendulous, like those of the black races, especially the Hottentots and Australians; it is a malformation frequent among idiots, and occurs together with prognathism and the flattened nose.
Another notable form is that in which the lips are not only thick and fleshy, but the internal tissues are so abnormally developed that they protrude from the oral orifice in a slight prolapsus; this form of lips is quite characteristic of myxedematous idiots. Finally, we may meet with the so-called hare-lip, or lip divided in the middle, signifying an arrest of embryonal development and frequently accompanied by a cleft palate and a double uvula (see Development of the face).
The Teeth.—There is nothing new to tell of the characteristic forms of the teeth—the incisors, the canines, the premolars, and the molars—nor of their regular placement in a single row corresponding to the curve of the maxilla and the mandible. I shall therefore merely give the two dental formulæ corresponding to the two dentitions of man.
First dentition, or "milk teeth":
| 2—2 | 1—1 | 2—2 | = 20 teeth |
| –—– | –—– | –—– | |
| 2—2 | 2—2 | 2—2 | |
| incisors | canines | premolars |
Second or final dentition:
| 2—2 | 1—1 | 2—2 | 3—3 | = 32 teeth |
| –—– | –—– | –—– | –—– | |
| 2—2 | 1—1 | 2—2 | 3—3 | |
| incisors | canines | premolar | molars |
In relation to the teeth there are a great number of anomalies which may occur, in number, in position, in size and form, and these anomalies are so frequent that we may say the smile stigmatizes the degenerate. Frequently it is the most evident stigma of the whole face; so much so that this same smile which adds so much charm to the normal human countenance becomes ugly and repulsive in degenerates.