Page:EB1911 - Volume 22.djvu/348

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334
PRIMATES


formula is i. %, c. }, p. § , m. aff, or the same as in American upper incisors are small and separated from

the lower ones are large and approximated

canine; the molars have three or four cus s

monkeys; but the

each other, while

to the incisor-like p .

In all cases the stomach is simple and a caecum present. The testicles are contained in a scrotum, the penis has a bone, the uterus is bicornuate and the urethra perforates the clitoris. The placenta may be either diffuse, with a large allantoic portion, and non-deciduate, or discoidal and deciduate. As a rule, only a single offspring is produced at a birth. Very noteworthy is the occurrence in the females of the Asiatic lorisis of what appears to be the vestige of a marsupial apparatus, attached to the front of the pelvis. Lemur catla also possesses the rudiment of a marsupial fold; while in both sexes of the aye-aye occurs a skin-muscle corresponding to the sphincter marsupii of marsupials.

The distribution of existing lemurs is very peculiar, the majority of the species inhabiting Madagascar, where they for the most part dwell in small patches of forest, and form about one-half the entire mammalian fauna of the island. The remaining species inhabit Africa south of the Sahara and the Indo-Malay countries.

Tarsier.-The tiny little large-eyed Malay lemuroid known as the tarsier, Tarsius spectrum (or T. tarsius), of the Malay Peninsula and islands, together with its Celebean and Philippine representatives, alone constitutes the section Tarsiina (and the family Tarsiidae), which has the following distinctive characteristics: The lower incisor is vertical and the canine of normal form, while the upper incisors are in contact; the orbit is cut off from the temporal fossa by a bony plate, leaving only a small orbital fissure; the tympanum enters into the formation of the auditory meatus, through which passes the canal for the internal carotid artery; the tibia and fibula in the hind-leg are fused together, and the calcaneum and navicular of the tarsus elongated. The tarsier seems to be a primitive form which makes a certain approximation to the Anthropoidea, and ditiers from other lemuroids' in the structure of its placenta. The dental formula is i. Q, c. 1-, p. § , m. § , total 34. Tarsiers have enormous eyes, occupying the whole front of the orbital region, and are purely nocturnal in their habits, living in trees on the branches of which they move by hopping, a power they possess owing to the elongation of the tarsal bones (see TARSIER). Malagasy Lemurs.~All the other Prosimiae may be grouped in a second section, the Lemurina, characterized as follows: The lower incisors and the canine are similar in form and inclined forwards (fig. I8); the upper incisors are small and separated by an interval in the middle line; the orbits communicate largely with the temporal fossae; the internal carotid artery enters the skull in advance of the auditory meatus through the foramen lacerum anterius; and the tibia and fibula are separate. The Mala asy lemurs are now all included in the single family Lemuridae, which is confined to Madagascar and the Comoro Islands, and characterized by the tympanic ring lying free in the auditory bulla. The typical sub-family Lemurinae, which includes the majority of the family group, is characterized by all the fingers except the index having fiat nails, the elongation of the facial portion of the skull, the large hemispheres of the brain not covering the cerebellum, the occasional prese'nce of two inguinal in addition to the normal pectoral teats, the dental formula 'i. %, c. }, p. § , m. § , with the first upper incisor generally small and sometimes wanting, and the hinder cusps of the upper molars smaller than the front ones. These lemurs are woolly-haired animals, often nearly as lar e as cats, with the legs longer than the arms, the tail long and bushy, and the spinal processes of the last dorsal and the lumbar vertebrae inclined. In the typical genus Lemur (fig. IQ), the tarsus is of normal length, the tail at least half as long as the body, the ears are tufted, there are no inguinal teats, the last premolar is not markedly broader than the others, and the upper molars have a conspicuous cingulum. These lemurs.have long fox-like faces, and habitually walk on the ground or on the branches of trees on all fours, although they can also jump with marvellous agility. They are gregarious, living in small troops, are diurnal in their habits, but most active towards evening, when they make the woods resound with their loud cries, and feed, not only on fruits and buds, but also on eggs, young birds and insects. When at rest or sleeping, they generally coil their long, bushy tails around their bodies, apparently for the sake of the warmth it affords. They have usually a single young one at a birth, which is at first nearly naked, and is carried about, hanging close to and almost concealed by the hair of the mother's belly. After a while the young lemur changes its position and mounts upon the mother's back, where it is carried about until able to climb and leap by itself. One of the most beautiful species is the ring-tailed lemur (L. catta, fig. 19), of a delicate rey colour, and with a long tail marked with alternating rings of biack and white. This is said by G. A. Shaw to be an exception to other lemurs in not being arboreal, but living chiefly among rocks and bushes. Pollen, however, says that it inhabits the forests of the south-west parts of Madagascar, living, like its conveners, in considerable troops, and not differing from them in its habits. He adds that it is extremely gentle, and active and graceful in its movements, and utters at intervals a little plaintive cry like that of a cat. All the others have the tail of uniform colour. The largest is L. varius, the ruffed lemur, sometimes black and white, and sometimes reddish-brown, the variation apparently not depending on sex or age, but on the individual. In L. m/.waco the male is black and the female red mongoz, L. fulvus and L. rubriventer are other well-known species. -


FIG. 19. Th€ Ring-tailed Lemur (Lemur cotta).

In 'all these lemurs the small upper incisors are not in contact with one another or with the canine, in front of which they are both placed. In the species of Hapalemur, on the other hand, the upper incisors are very small, sub-equal and separated widely in the middle line; thoseof each side in Contact with each other and with the canine, the posterior one being placed on the inside, and not in front of the latter. Muzzle very short and truncated. Two inguinal teats, in addition to the normal pectoral pair, are present. The last premolar is broader than those in front, and the upper molars lack a distinct cingulum. The typical H. g1iseus is smaller than any of the true lemurs, of a dark-grey colour, with round face and short ears. It is quite nocturnal, and lives chiefly among bamboos, subsisting on the young shoots. The second species has been named H. simus. In Hapalemur there is no free centrale to the carpus, and the same is the case with the six or seven species of Lepidolemur (Lepilemur), in which the first upper incisor is rudimentary or wanting, while the second may also be wanting in the adult. There are small lemurs, with small premaxillae, short snouts, tails shorter than the body, bladder-like mastoid processes, and the upper molars with an inconspicuous cingulum and the hind-cusps of the last two rudimentary; the fourth upper premolar being relatively broad. Mixocebus caniceps is an allied generic type (see LEMUR).

The small Malagasy lemurs of the genera Chirogale, Micracebus and Opolemur differ from the preceding in the elongation of the calcaneum and navicular of the tarsus, on which grounds they have been affiliated to the African galagos. The difference in the structure of the tympanum in the two groups indicates, however, that the elongation of the tarsus has been independently developed in each group. These lemurs have short, rounded skulls, large eyes, long hind limbs and tail, large ears, the first upper incisor larger than the second, the last upper premolar much smaller than the first molar and furnished with only one outer cusp, and the mastoid not bladder-like. Some are less than a rat in size, and all are nocturnal. One of the largest, Microcebus fufcifer, is reddish-grey, and distinguished by a dark median stripe on its back which divides on the top of the head into two branches, one of which passes forwards above each eye. The most interesting peculiarity of these