The Simiadae

b. In the great group of the Simiadae, which contains the Apes and Monkeys, the attitude is sometimes habitually quadrupedal, the axis of the body being horizontal; but, in a few species, the trunk is habitually held in a more inclined position, and the animals readily assume the erect attitude.

The Simiadae are sometimes terrestrial in habit, and good runners, but they are always excellent climbers, and, in some cases, they are necessitated by their organization to be almost as thoroughly arboreal as the Sloths.

The hallux is always much shorter than the second digit of the foot, and capable of very free movement in adduction and abduction.

The series of the teeth, in each jaw, is interrupted by a diastema in front of the canine in the upper jaw, and behind it, in the lower; and the canine teeth are longer than the others, the points of their crowns projecting for a greater or less distance beyond the rest.

In the skull, the length of the basi-cranial axis equals more than half the extreme length of the cavity which contains the brain. The absolute capacity of the cranium is less than forty cubic inches; and, if there is any difference in the length and abundance of the hair which covers the body, it is longest on the back. The uterus is undivided, and the elitoris is not perforated by the urethra. The teats are only two in number, and they are pectoral.

The Simiadae are divisible into three families-the Arctopithecini, the Platyrrhini, and the Catarrhini.