The last and lowest representatives of the Cebidae constitute
the sub-family Nyctipithecinae, the members of which are cat-like
monkeys, with woolly or bushy hair, short, conical muzzles,
non-prehensile tails and well-developed thumbs. The brain-case of
the skull is not elongated, and the hemispheres of the brain do
not cover the cerebellum. The lumbar vertebrae are elongated,
with long, sharp, backwardly directed spinal processes; the hinder
part of the lower jaw is tall; and there is no laryngeal sac. The
long and hooked caecum has its terminal portion constricted. In
accordance with their nocturnal habits, the douroucoulis
(Nyctipithecus) are easily recognized by their large and closely approximated
eyes, which are, however, separated by a complete septum,
the comparatively narrow nasal septum, small ears buried in the
woolly fur, and long bushy tail. Well-known species are the
lemur-like douroucouli (N. felinus, fig. 15) of Amazonia, Peru and
Ecuador, and N. vociferans, with a nearly similar distribution.
The titis, Callithrix (or Callicebus[1]), are smaller monkeys (fig. 16),
with more forwardly directed eyes, which are not surrounded by a
radiating fringe of hair and a wider nasal septum. The titis are
represented by about ten species, of which C. moloch is represented
in fig. 16. Most of them are confined to Amazonia, but a few
among them C. moloch, reach the east coast. Like the marmosets,
they feed largely upon insects and grubs.
Fig. 16.-The Moloch Titi (Callithrix moloch).
Fig. 17.-The Golden Marmoset (Hapale chrysoleuca).
The second and last family of the Platyrrhina is represented by the marmosets or oustitis (Hapalidae), all of which are small monkeys, with the ears hairy externally, and the nails, except that of the great toe, claw-like, the thumb non-opposable, the tail long, bushy and non-prehensile, and only two molars in each jaw, the dental formula thus being i. 22, c. 11, p. 33, m. 22. The humerus has no entepicondylar foramen. Three young are produced at a birth. Marmosets are divided into two genera, those in which the lower canines are not markedly larger than the incisors constituting the typical Hapale, while such as have the lower canines taller than the teeth between them form the genus Midas. These squirrel-like little monkeys, in which the great toe can be opposed to the other toes, range as far north as 15° N., where they are represented by Midas geoffroyi, and as far in the opposite direction as the southern tropic, where M. chrysopygus and M. rosalia occur. The colour and the length of the hair are very variable, some species having long silky pale-chestnut hair (fig. 17) and tufted ears, while in others the hair is comparatively short and black, or black with brown bars, while the ears are not tufted (see Marmoset).
Fig. 18.-Skull of Ring-tailed Lemur (Lemur catta).
| uc, | Upper canine. | | pm, | Premolars. |
| lc, | Lower canine. | m, | True molars. |
Lemurs, Prosimiae.—Although the likeness generally takes the form of a more or less grotesque caricature, the faces of all monkeys and apes present, in greater or less degree, some resemblance to the human countenance. In the lower group of Primates, commonly known as lemurs, or lemuroids, this resemblance is wholly lost, and the face assumes an elongated and fox-like form, totally devoid of that “expression” which is so characteristic of man and the higher apes and monkeys. Lemurs, Prosimiae or Lemuroidea, which form a group confined to the tropical regions of the Old World and more numerously represented in Madagascar than elsewhere, are arboreal and for the most part crepuscular or nocturnal Primates, feeding on insects or fruits, or both together and collectively characterized as follows. The tail, which is generally long and thickly haired, is never prehensile. As a rule, there is a single pair of pectoral teats, but an additional abdominal or even inguinal pair may be present. The thumb and great toe are opposable to the other digits, the former being provided with a flat nail, while the second toe is always furnished with a claw; the fourth toe is longer than all the rest, and the second, or index, finger is small or rudimentary. In the skull (fig. 18) the orbital ring is formed by the frontal and jugal bones, and, except in the Tarsiidae, there is a free communication between the orbit and the temporal fossa; the lachrymal foramen is situated outside the orbit (fig. 18), the tympanic either forms a free semicircle in the auditory bulla or enters into the formation of the latter; and the foramen rotundum is generally fused into the spheroidal fissure. Interparietal bones are frequently developed, and the two halves of the lower jaw are generally welded together in front. Except in the genus Perodicticus, the humerus is furnished with an entepicondylar foramen at the lower end; the centrale of the carpus is generally free; and the femur is usually provided with a third trochanter. The cerebellum is only partially covered by the hemispheres of the brain, which in the medium-sized and larger species conform to the general type of the same parts in monkeys and apes. The normal dental
- ↑ Apparently the name Callithrix was originally given to the marmosets, and if transferred to that group should be replaced by Callicebus.
