_The Teeth._ These are specially important, for criminals rarely have normal dentition. The incisors show the greatest number of anomalies. Sometimes both the lateral incisors are absent and the middle ones are of excessive size, a peculiarity which recalls the incisors of rodents. The teeth are frequently striated transversely or set very wide apart (diastema) with gaps on either side of the upper canines into which the lower ones fit, a simian characteristic. In some cases, these spaces occur between the middle incisors or between these and the lateral ones.
Very often the teeth show a strange uniformity, which recalls the homodontism of the lower vertebrates. In some cases, however, this uniformity is limited to the premolars, which are furnished with tubercles like the molars, a peculiarity of gorillas and orang-outangs. In 4% the canines are very strongly developed, long, sharp, and curving inwardly as in carnivores. Premature caries is common.
_The Chin._ Generally speaking, this part of the face projects moderately in Europeans. In criminals it is often small and receding, as in children, or else excessively long, short or flat, as in apes.
_Wrinkles._ Although common to normal individuals, the abundance, variety, and precocity of wrinkles almost invariably manifested by criminals, cannot fail to strike the observer. The following are the most common: horizontal and vertical lines on the forehead, horizontal and circumflex lines at the root of the nose, the so-called crow's-feet on the temple at the outer corners of the eyes, naso-labial wrinkles around the region of the mouth and nose.
_The Hair._ The hair of the scalp, cheeks and chin, eyebrows, and other parts of the body, shows a number of anomalies. In general it may be said that in the distribution of hair, criminals of both sexes tend to exhibit characteristics of the opposite sex. Dark hair prevails especially in murderers, and curly and woolly hair in swindlers. Both grey hair and baldness are rare and when found make their appearance later in life than in the case of normal individuals. The beard is scanty and frequently missing altogether. On the other hand, the forehead is often covered with down. The eyebrows are bushy and tend to meet across the nose. Sometimes they grow in a slanting direction and give the face a satyr-like expression (see Fig. 5).