The Cambridge Natural History Part 45

_Nyctinomus_ is an allied genus, and also has many species. These range through both hemispheres. The chief differences from _Molossus_ are that the premaxillary bones are separate in front or united by cartilage, and that the incisors may be three in the lower jaw.

FAM. 5. PHYLLOSTOMATIDAE.--The Bats of this family are extremely numerous and almost entirely confined to South America. None of them occur outside the New World. There are some thirty-five genera. The members of the family are to be distinguished by the presence of the nose leaf, by the well-developed premaxillae, and by the possession of three phalanges by the middle finger. They are large, and the tragus of the ear is well developed.

_Vampyrus_ of South America contains the large species V. spectrum, which, mainly on account as it seems of its "forbidding aspect," was supposed to be a bloodsucker. This genus has two incisors on each side of the upper jaw.

The genus _Glossophaga_ represents another type of structure in this family. The tongue is long and extensile, and is much attenuated towards the tip, where it is covered with strong and recurved papillae. This structure was at one time thought to indicate a {532} bloodsucking habit; but its use appears to be merely that of scooping out the soft insides of fruits, upon which the Bat mainly lives. The incisors are only one on each side of the upper jaw. The really bloodsucking Bats of this family belong to the genera _Desmodus_ and _Diphylla_. The former is the Vampire, the species being known as _Desmodus rufus_. These Bats have no tail; there is no true molar tooth; the canines are large, and the single pair of upper incisors quite caniniform, and very sharp and strong. These are the main teeth for aggression. In accordance with its diet of blood, the Vampire has a peculiarly modified intestine. The gullet is provided with a bore so small that nothing but fluid food could pa.s.s down it; the stomach is intestiniform in shape.

{533}

CHAPTER XVII

PRIMATES

ORDER XIII. PRIMATES.

The highest of mammals, the Primates,[404] may be thus differentiated from other groups:--Completely hairy, generally arboreal mammals, with five digits on fore- and hind-limbs, provided with flat nails (except in the case of certain Lemurs and the Marmosets), the phalanges that bear these being flattened at the extremity and expanded rather than diminished in size. The fore-feet are grasping hands as a rule, and the hind-feet walking as well as (generally) grasping organs, and the mode of progression is plantigrade. The teats, except in _Chiromys_, are thoracic, and even axillary in position. The skull is characterised by the fact that the orbital and the temporal vacuities are, at least partly, separated by bone.

The clavicles are always present. The carpus has separate lunar and scaphoid bones, and the centrale is often present. There is rarely an entepicondylar foramen in the humerus, except in some archaic Lemurs. The femur has no third trochanter. The stomach is usually simple, being sacculated only in Semnopithecinae. The caec.u.m is always present, and often large.

This great group could be easily divided into two separate orders, the Apes and the Lemurs, if it were not for certain fossil types. As will be seen from the description of _Nesopithecus_ and of _Tarsius_, the actual hard and fast lines between _all_ Apes and _all_ Lemurs are very few. On the other hand, it is a little difficult to draw a hard and fast line between the Primates as a whole--or at least between the Lemurine section--and the Creodonta, a {534} group to which so many others appear to converge. It is disputed, for example, whether the Chriacidae among extinct Lemurs are rightly placed, or whether they should be referred to the Creodonta. The number of primitive characters seen among the Primates, even in Man himself, is remarkable. Of these the more important are the five digits of both limbs and the plantigrade walk, the presence of clavicles and of a centrale, and the absence of a third trochanter. All these features distinguish the early Eutheria.

SUB-ORDER 1. LEMUROIDEA.[405]

The animals known as Lemurs, from their nocturnal and ghostly habits, are on a lower level of organisation than the other division of the Primates.

Even the external form enables the members of the present sub-order to be readily distinguished from the higher Anthropoidea. The head is more like that of a Fox, with a sharp muzzle; it lacks the human expression of the face of even the lower among the Apes. The long tail is never prehensile, and there is never any trace of cheek pouches or of integumental callosities, which are frequently so characteristic of the Apes. The Lemurs agree with the remainder of the Primates in having pectoral mammae (sometimes abdominal ones are present in addition, and in _Hapalemur_--in the male at least--there is a mamma upon each shoulder), in having opposable thumbs and toes, and in the flattened digits. The tail varies from complete absence (in the _Loris_) to a great length and bushiness in the Aye-aye. The pectoral limbs are always shorter than the hind-limbs; the reverse is occasionally the case in the Anthropoidea. A curious contrast between the two divisions of the Primates concerns the digits of the hands and feet. In the Anthropoidea it is the hallux or pollex which is subject to great variation. In the Lemurs, on the contrary, the thumb and great toe are always well developed, but the second or the third digit constantly shows some abnormality; thus the singular elongation of the third digit of the hand in _Chiromys_ and the absence of the index in the _Potto_.[406] In all Lemurs the {535} second toe is furnished with a sharp nail, unlike the flattened nails of the other fingers and toes, and in _Tarsius_ the third also is thus provided. As to osteology, the shape of the head, already referred to, indicates some of the differences in the skull which mark off the Lemurs from the Anthropoidea. The brain case is small relatively to the face; the orbital and temporal fossae are in communication, though the frontal and jugal bones are united behind the orbit. The two halves of the lower jaw are not invariably ossified to form one piece, as is the case with most Apes. The lachrymal foramen lies upon the face in front of the orbit. The teeth are characteristic, not so much in their number (the dental formula is usually I 2, C 1, Pm 3, M 3 = 36) as in the disposition of the incisors. The incisors of the lower jaw and the canines project forwards in a way only found in a few American Monkeys; as in the Apes there are four incisors in each jaw, but, with the exception of the highly aberrant _Chiromys_, there is a s.p.a.ce in the upper jaw between the incisors of the two sides. The canines of the lower jaw, moreover, are often incisiform. There is a well-developed sublingua beneath the tongue (see p.

61). The stomach is perfectly simple; and the caec.u.m, always present and varying in length, never has a vermiform appendix. The gall-bladder is always present. The brain differs from that of the Anthropoidea in that the cerebellum is, as in the lower Mammalia, exposed. The convolutions upon the cerebral hemispheres are not greatly developed, a circ.u.mstance, however, which (see p. 77) may have more relation to the size of the animals than to their mental development. Though the brain in its general outlines is not like that of the other Primates, there are certain resemblances; the most striking of these is perhaps the presence, though in rather a rudimentary condition, of the "Simian fissure."

The Lemurine brain has been chiefly studied by Flower,[407] by Milne-Edwards,[408] and by myself.[409] There are also a number of scattered papers dealing with particular types, such as the memoirs of Owen[410] and Oudemans,[411] upon the brain (and the general anatomy) of _Chiromys_. Without going into great {536} detail it may be stated generally that the anatomy of the brain of this group confirms the cla.s.sification which is adopted in this work.

A curious feature in the anatomy of the Lemurs, which they share with animals so remote from them in the system as the Edentata, is the breaking up of some of the arteries of the limbs to form retia mirabilia; nothing of the kind is known among the other Primates.

Perhaps the most remarkable difference between the Lemurs and the Anthropoidea, which are really in many respects more closely allied than might be inferred from the above summary of differences, is in the structure of the placenta. The Lemurs agree with the Ungulates in having a non-deciduate placenta.

A curious feature confined to the sub-family Lemurinae was first discovered by myself in _Hapalemur griseus_.[412] On the forearm (see Fig. 258) is an area of hardened skin, which is raised into spine-like processes. Fully developed, this organ is characteristic of the male, the area being marked off in the female, but without the spiny outgrowths. On removing the skin a gland about the size and shape of an almond is brought into view. In other Lemurs there is no modified skin, but a small tuft of particularly long hairs, which are also present in _Hapalemur_, and a small gland beneath the skin. The gland of _Hapalemur_ may be comparable with a tract of hardened skin in _Lemur catta_, which projects to a large extent and has been spoken of as a "climbing organ."

An almost exactly similar tuft of spine-like outgrowths exists upon the lower end of the ankle of _Galago garnetti_. The spines are black and bent, just as they are in _Hapalemur_. There appears also to be a gland. This structure is not universal in the genus _Galago_ any more than is the patch of spines in the genus _Hapalemur_.

In addition to this gland and to the patch of spines which cover it, the same Lemur as well as _Chirogaleus_ and certain species of _Lemur_ possess to the inner side of it a bundle of long and stiff bristles a.s.sociated with unusually large sebaceous glands; these structures are, of course, not h.o.m.ologous with the gland of the arm of _Hapalemur_, as they coexist in the same {537} species. They are, moreover, not peculiar to the Lemurs, but exist in the Squirrel, in the Domestic Cat, in the Leopard, in _Ba.s.saricyon_,[413] the Otter, various Marsupials, and doubtless in many mammals which require a tactile organ, for these hairs are a.s.sociated with a large branch of the radial nerve.

[Ill.u.s.tration]

FIG. 258.--A, left arm of _Hapalemur griseus_ [male]. __a__, Teat; _b_, spines on arm gland; _c_, tactile bristle. B, left foot of _Nycticebus tardigradus_. 1 to 5, Pads upon sole of foot. (After Sutton, and Mivart and Murie.[414])

The Lemurs have at the present time a most remarkable distribution. There are altogether about fifty species, referable to seventeen genera.

Thirty-six species are confined to Madagascar {538} and to some small neighbouring islands. The rest occur in the Ethiopian and in the Oriental region. The rest of the world is at present totally without Lemurs, though, as will be seen in the sequel, the order was more widely spread over the globe in past times.

FAM. 1. LEMURIDAE.--This family can be usefully subdivided into four sub-families.

SUB-FAM. 1. INDRISINAE.--This sub-family is limited to Madagascar, and has been exhaustively treated of by M. Grandidier and Professor Milne-Edwards in the _Histoire de Madagascar_. These Lemurs contrast with others by the large size of the hind- as compared with the fore-limbs. The ears are short. The tail varies in length. The thumb is but slightly opposable, and the toes are webbed. Correlated with the first two of these characters, these Lemurs when upon the ground progress by means of the hind-limbs, holding their arms above their heads. The number of teeth is reduced, the total being thirty. The formula[415] is I 2/2 C 1/0 Pm 2/2 M 3/3. The colon or large intestine, as figured by Milne-Edwards, has a remarkable watch-spring-like coil, highly suggestive of the Ruminants and of certain Rodents. This, however, is only in _Propithecus_ and _Avahis_. The caec.u.m in this sub-family is specially large. The brain is characterised by the comparatively slight development of the angular fissure in _Propithecus_ and _Avahis_; it is in them anterior in position. In _Indris_ it is more [416]-shaped and larger as in _Lemur_. The parieto-occipital fissure is fairly well developed, so too is the antero-temporal.

The genus _Indris_ has more p.r.o.nounced external ears than have the two other genera of the sub-family. The tail is rudimentary. The incisors of the upper jaw are sub-equal and set close together, those of the lower jaw have marked longitudinal ridges upon the outer surface, which suggests _Galeopithecus_ (see p. 520). The molars are quadricuspidate. There is but a single species, _I. brevicaudata_, which is of a black colour, diversified with white upon the rump and the limbs. The term "Indri"[417]

means, as does "Aye-aye," "look." One of the native names for the {539} animal, "Amboa.n.a.la," signifies "dog of the forest," and is derived not only from the woeful howls of the creature, but from the fact that in certain parts of the island it is used as a dog to chase birds.

These howls are largely effected by means of a laryngeal pouch, which is described as different from that of Apes; the mechanism must also differ from that of _Megaladapis_, inasmuch as the lower jaw is not deep as in that extinct Lemur. The Indri is the largest of Lemurs, measuring about two feet in length. It is arboreal and social, travelling in large companies.

As is the case with the _Propithecus_, the natives of Madagascar hold the Indri in awe and veneration. It is curious that the name Lemur or ghost is peculiarly applicable to the Indri or Babakote in another sense from that which led to its adoption by Linnaeus. The natives, in fact, believe that men after death become Indris. Naturally, therefore, these Lemurs have reaped the advantage of this superst.i.tion in almost perfect immunity from destruction. Their "long-drawn-out, melancholy cries" are probably at the root of much of the ghostly terrors which they inspire.

The genus _Avahis_[418] has but a single species, _A. laniger_, which is the smallest of this sub-family. It is a foot long without the tail. The Avahi has a long tail (15 inches in length) like _Propithecus_. The outer incisors are larger than the inner, thus differentiating the genus from _Propithecus_. The molars of the upper jaw are quadricuspidate, of the lower jaw five cusped. This genus has only eleven pairs of ribs instead of the twelve of _Indris_ and _Propithecus_. The Avahis, unlike the Sifakas and Indrinas, lead a solitary life, or go about in pairs. They are, moreover, completely nocturnal.

The genus _Propithecus_ is characterised by the fur being rather silky than woolly, which latter is the kind of fur found in the two other genera of the sub-family. They are also rather larger animals, the body reaching a length of nearly 2 feet. The tail is long as in _Avahis_; the inner incisors are larger than the outer. The "Sifakas," as these Lemurs are termed, have a reputation for gentleness of character, but, as is the case with other animals, the males fight for the possession of the females at the breeding season. They are mainly vegetarian in habit, and travel in large companies. There are at least three species, and {540} several varieties are allowed. The colours of these Lemurs are bright, and distributed so as to form contrasting bands; thus _P. coquereli_, a variety of _P. verreauxi_, has a black face and a body mainly white, with splashes of a rich maroon upon the limbs and upon the chest.

These Lemurs are diurnal, and are especially active in the early morning and evening, sleeping, or at any rate remaining quiet, during the heat of the day. Their fitness for an arboreal life is shown by the existence of a parachute-like fold of skin between the arms and the body, which suggests a commencement of the more complete parachute of Flying Foxes, etc. These Lemurs are said to be reverenced and therefore shielded from injury by the natives of Madagascar.

SUB-FAM. 2. LEMURINAE.--The "True Lemurs" are all inhabitants of Madagascar and of the Comoro Islands. They have not such long hind-limbs as have the members of the last sub-family, nor are the toes webbed. The tooth formula differs from that of the Indrisinae in that there is one more premolar on each side of the upper jaw, and often one more incisor in the lower jaw, making thus a total of thirty-six teeth. Sometimes, however, the incisors of the upper jaw are totally wanting.

The Hattock, genus _Mixocebus_, is a scarce creature, only known from a single species, _M. caniceps_. As it is rare, nothing is known of its habits. It has one pair of upper incisors. The creature is one foot and half an inch long, exclusive of the tail, which is an inch longer than the body.

Genus _Lepilemur_.--The Lemurs belonging to this genus, entirely confined to Madagascar, as are all the Lemurinae, have received the perfectly unnecessary and pseudo-vernacular name of "Sportive Lemurs"; an equally inappropriate and not at all ingenious name of "Gentle Lemurs" being bestowed upon the allied genus _Hapalemur_. In _Lepilemur_ there are seven species, which are to be distinguished from _Mixocebus_ in having the tail shorter than the body. There are no incisors in the upper jaw. The last molar is tricuspidate in the upper jaw; that of the lower jaw has five cusps. They are nocturnal creatures, and but little is known of their habits. Previously to Dr. Forsyth Major's visit to Madagascar only two species of the genus were known; he has added five others. The length of the body is 14 inches, and that of the tail 10 inches, in _L. mustelinus_, which is the largest species. {541}

The genus _Hapalemur_[419] has a shorter muzzle than _Lemur_, and shorter ears. There are two pairs of mammae instead of only one; these are upon the breast and abdomen. In the male there is a pair upon the shoulder. The incisors are small, sub-equal, and placed one behind the other; the last one is at the inside of the canines. The molars of the upper jaw and the last premolar have only three well-marked cusps; in the lower jaw they have four. The caec.u.m is blunter and is not so long as in _Lemur_; it differs from that of other Lemurinae in having only two supporting mesenteries, which are both furnished with blood-vessels. As in _Lepilemur_ and the Indrisinae the carpus has no os centrale.

The genus, which is confined to the island of Madagascar, has two species, of which one, _H. simus_, is the larger and has a broader muzzle, and does not possess the peculiar arm gland (Fig. 258) already described in _H.

griseus_. The former species is stated by Mr. Shaw to be chiefly a gra.s.s-eater, and to dislike berries and fruits, which are usually so popular with Lemurs. It is, however, believed by some that there is but one species of _Hapalemur_. _H. griseus_ is 15 inches long, and has a tail of the same length. Its native name is "Bokombouli." It is nocturnal, and is especially addicted to bamboos, upon the shoots of which it feeds and among which it lives. It is often exhibited in the Zoological Society's Gardens; but the specimens seem to be always males. This Lemur is of a dark iron-grey colour with a tinge of yellow, more marked in individuals which have received the separate specific name of _H. olivaceus_.

The genus _Lemur_ is distinguished by the long tail, half as long as the body at the least, by the elongated face, and by the Fox-like muzzle; the teeth are present to the full number of the family, viz. thirty-six; the incisors are small and equal in size, and are separated from each other and from the canines by s.p.a.ces. The molars of the upper jaw have five cusps, but there are only four in the lower jaw.

This genus is entirely confined to Madagascar and the Comoro Islands, and consists of several species, the exact number of which is doubtful. Wallace in his _Geographical Distribution_ allows fifteen; Dr. Forbes only eight, with a plentiful allowance of varieties. One of the best-known species is _Lemur catta_, the {542} Ring-tailed Lemur, or the "Madagascar Cat" of sailors. _Lemur macaco_ shows a remarkable s.e.xual dimorphism, the male being black, and the female--formerly described as a distinct species, _L.

leucomystax_--being reddish brown with white whiskers and ear tufts. This led to a confusion with a totally distinct species, _L. rufipes_, of which the male (regarded as distinct and called _L. nigerrimus_) is entirely black. This latter identification is, however, considered by Dr. Forsyth Major[420] to be not quite certain at present.

The young Lemur is at least sometimes carried by the mother across her belly; its tail pa.s.ses round her back and then round its own neck.

[Ill.u.s.tration]

FIG. 259.--Ruffed Lemur. _Lemur varius._ 1/9.

The Lemurs of this genus agree with those of some other genera in the loudness of their voice, which is constantly exercised. Some move about by day and others by night. They are insectivorous and carnivorous as well as vegetarian; and Mr. Lydekker suggests[421] that their abundance and hardiness is to be traced to this fondness for a mixed diet. _Lemur catta_ seems to be the only member of the genus that is not arboreal. It lives among rocks where but few trees, and those much stunted, occur. Many species of _Lemur_ are always to be seen in the Zoological Society's Gardens. Fourteen "species" have at one time or another been exhibited.

SUB-FAM. 3. GALAGININAE.--This sub-family is found on the continent of Africa as well as in Madagascar; but the genera are {543} different in the two districts. In Madagascar we have _Opolemur_, _Microcebus_, and _Chirogale_; on the continent, _Galago_. The members of this sub-family have markedly large ears, which are but little furry; the tail is long. A very marked skeletal character distinguishes this sub-family from other Lemuridae, and allies them to _Tarsius_, that is the lengthening of the calcaneum and naviculare in the ankle. The dental formula is as in _Lemur_.

The supporting bands of the caec.u.m are in this sub-family as in the genus _Lemur_. There are but two folds, of which one is median and non-vascular; the lateral fold bears a blood-vessel, and is joined by the median frenum.

The brain is but little known. The only figure of the brain of _Galago_ is one by myself. There are four mammae, two on the breast and two upon the abdomen.

The genus _Galago_ comprises at any rate six distinct species. They are all African, and range right across the continent from Abyssinia as far south as Natal, and to Senegambia in the west. The incisors of the upper jaw are small and equal; there is a gap between the canine and the first premolar.

The molars and the last premolar have four cusps; the last molar of the lower jaw has an additional fifth cusp as in _Macacus_, etc. The Galagos are chiefly nocturnal, and are more or less omnivorous. Owing to their long hind-legs these animals when they leave the trees advance upon the ground by hops like a Kangaroo. _Galago senegalensis_ makes a nest in the fork of two branches, where it sleeps during the day. The Great Galago (_G.

cra.s.sicaudatus_) is named by the Portuguese "Rat of the Cocoa-nut Palm."

Sir John Kirk, after whom a variety of this species is called, relates that it is incapable of resisting the fascinations of palm wine, upon which it will readily intoxicate itself, and as a consequence brave probable captivity. I have referred above (p. 536) to the patch of spines upon the tarsus of _G. garnetti_.

The genus _Chirogale_ is entirely confined to Madagascar. It is to be distinguished from _Galago_ by the fact that the inner incisors are larger than the outer. There are five species of the genus known: four previously to Dr. Forsyth Major's recent visit to Madagascar, and a fifth brought back by him.[422] In connexion with this genus the naturalist just mentioned has observed that all the Lemurs of Madagascar, including the aberrant {544} _Chiromys_, differ from the African forms by the fact that the tympanic ring "is completely enclosed by the bulla ossea, but without osseous connexion with the same." This character he thinks so important as to justify the inclusion of all the Mascarene forms in one group as opposed to another group consisting of the continental Lemurs. In this event _Chirogale_ will have to be separated from its close a.s.sociation with _Galago_. For the present, however, it is left in the more generally accepted position.