Page:Encyclopædia Britannica, Ninth Edition, v. 15.djvu/423

Rh ISrSECTIVORA.] lobes, the right and left lateral being cut off by deep fissures ; both the caudate and Spigelian lobes are generally well developed, and the gall-bladder, usually large and globular, is placed on the middle of the posterior surface of the right central lobe. In most of the species (Soricidx, Centetido?, Chryso- ckloridse) the penis is capable of being more or less com pletely retracted within the fold of integument surrounding the anus ; in some (Galeopithedd t Taljiidx) it is pendent in front of the anus, while in others (Macroscelidx, Erinaceidse, Solenodontidx) it is carried forwards and suspended from the abdominal wall. In Centetinx and Chrysochloris the testes lie immediately behind the kidneys, in others more or less within the pelvis. During the rut they become greatly enlarged, forming protrusions in the inguinal region. Except in Rhynchocyon the uterine cornua are long and open into a short corpus uteri, which in many species (Soricidae, Talpidx, Centetidee, Chrysochloridsi) is not separated from the vagina by a distinct os uteri. With the exception of Galeopitliecus all Insectivora, appear to be multiparous, the number of foetuses varying from two to eight in Erinaceus, and from twelve to twenty-one in Centetes. The position of the mammary glands and the number of the teats vary greatly. In Galeopitliecus there are two pairs of axillary teats, in Solenodon a single pair post-inguinal, but in most species they range from the thorax to the abdomen, varying from two pairs in Gymnura to twelve in Centetes. In Chrysochloris the thoracic and inguinal teats are lodged in deep cup-shaped depressions. Odoriferous glands exist in many species. In most Shrews they occur on the sides of the body at a short distance behind the axilla, and their exudation is probably protective, as few carnivorous animals will eat their dead bodies. In both species of Gymnura and in Potamogale large pouches are situated on either side of the rectum, and discharge their secretions by ducts, opening in the first- named genus in front of and in the latter within the margin of the anus. In Centetes racemose glands similarly situated discharge by pores opening at the bottom of deep pits placed at either side of the anus. The integument is thin, but in many species lined with well-developed muscles, which are probably more developed in the Hedgehogs (Erinaceidss) than in any other mammal ; in this family and in Centetidse, most of the species are protected by spines implanted in the panniculus carnosus, and more or less replacing the fur of the upper surface of the body. The Insectivora are divisible into two very distinct suborders, of which the first includes a single genus only. SUBORDER I. Dermoptera. Upper and lower incisors compressed, multicuspidate, the lower deeply pectinate ; anterior and posterior limbs connected by a broad integumentary expansion forming a parachute. Family I. Galco- pithccidtB. SUBORDER II. Insectivora Vera. Upper and lower incisors conical, unicuspidate or with basal cusps only, the lower not pectinate ; limbs free, formed for terrestrial progression. I. Upper true molars broad, multicuspidate, with more or less well-defined W-shaped crowns. A. Symphysis pubis long ; intestinal canal generally with a caecum ; cerebral cavity comparatively large. a. Orbital ring encircled by bone ; metatarsus moderate ; arboreal. Family II. Tupaiidte. b. Orbital ring not encircled by bone ; metatarsus greatly elongated ; terrestrial. Family III. Afacroscelidfv. B. Symphysis pubis short or none ; intestinal canal without csecum ; cerebral cavity small ; skull without post- orbital processes. a. First and second upper molars with a central fifth cusp. a. Tympanics annular, not forming bullae. Family I V. Erinaceidse. A L 1 A 401 b. No central fifth cusp ; crowns of the upper molars W-shaped. a. Tympanics annular, not forming bulla. ; no zygo- matic arches. Family V. Soricidse. b. Tympanics forming bulls; ; zygomatie arches de veloped. Family VI. Talpidse. II. Upper true molars narrow, with V-shaped crowns. a. Tympanics annular, nut forming bulke ; zygomatie arches imperfect. a&quot;. No clavicles. Family VII. Potamogalidss. b&quot;. Clavicles well developed. a &quot;. Skull constricted between the orbits ; penis suspended. Family VIII. Solenodontidse. b. Sknll not constricted ; penis pendent, retractible. Family IX. Centdidss. b. Tympanics forming bailee ; zygomatie arches well- developed. Family X. Chnjsochloridae. Family GALEOPITHECIDJE. The characters of the family are those of the suborder Dermoptera, to which may be added that the orbit is nearly sur rounded by bone, the zygomatie arches are well developed, the tympanics form bulhe osscae, the ulna is distally united with the radius, the tibia and fibula are distinct, the pubic symphysis is long, the penis is pendent, the testes are received into inguinal pouches, the mammae are axillary, the uterus is two-horned, and there is a large caecum. Galeopitkecus (i f-, c f, pm |, m f ; second upper incisors and canines with two roots), with two species G.volans and G. philip- pinensis. The former, the Flying Lemur of Linnaeus, distinguished from the latter by the form of the upper incisors, has a total length of nearly 2 feet. The long and slender limbs are connected by a broad integumentary expansion extending outwards from the sides FIG. 5D. Feet of Galeopithecus philippinentii. of the neck and body, and forming also a web between the fingers and toes as far as the base of the claws (fig. 53) ; the hind limbs are further connected by a similar expansion passing outwards along the back of the feet to the base of the claws, and, inwardly, involving the long tail to the tip, forming a true interfemoral membrane, as in the Bats. The species of this family live in the forests of the Malay Peninsula, Sumatra, Borneo, and the Philippine Islands, where they feed chieily on the leaves of trees, and probably also on insects. Their habits are nocturnal, and during the daytime they cling to the trunks or limbs of trees head downwards in a state of repose. With the approach of night their season of activity commences, when they may be occasionally seen gliding from tree to tree supported on their cutaneous parachute, and they have been noticed as capable of traversing in this way a space of 70 yards with a descent of only about one in five. Galcopilhecus was referred by some of the older zoologists and anatomists to the Bats, and by others (and even in lately published works) to the Lemurs, but Professor Peters s view (in which most subsequent writers agree) that it belongs to neither of these orders, and must be considered an aberrant Insrctivore, appears to be undoubtedly the correct one. Besides differing from the Bats altogether in the form of the anterior limbs and of the double -rooted outer incisors and canines, it also contrasts strongly with them in the presence of a large sacculated caecum, and in the great length of the colon, which is so remarkably short in all the Chiroptera. From the Lemurs, on the other hand, the form of the brain, tho character of the teeth, the structure of the skull, and the deciduate discoidal placenta at once separate it. Family TUPAIID.E. Arboreal Insectivora, with comparatively large brain case, orbits encircled with bone, and well-developed zygomatie arches. The malar bone is perforated ; the tympanics form bullre ; the pubic symphysis is long ; the tibia and fibula are distinct, the meta tarsus but little longer than the tarsus ; the molars are broad, with XV. 51