402 MAMMALIA [INSECTIVORA. W-shaped cusps ; and the intestinal canal has generally a short crecum. The animals included in this family are all arboreal, resembling Squirrels closely both in habits and in external form ; they are divided into two genera having the same dental formula (i f , c |, pm f , m f ), but distinguished by the form of the skull. Tupaia, with nine species, is found in India, Burmah, the Malay Peninsula, Nicobars, Sumatra, Java, and Borneo. The species closely resemble one another, differing chiefly in size and in the colour and length of the fur. Nearly all have long bushy tails, which still further FIG. 51. Pentail (Ptilocercus lowii). x J. From Gray, Proc. Zool. Soc., 1848. increase their resemblance to Squirrels. Their food consists of insects and fruit, which they usually seek for in the trees, but also occasionally on the ground. When feeding they often sit on their haunches, holding the food, after the manner of Squirrels, between their fore paws. Ptilocercus includes a single very interesting species, Pt. lowii, inhabiting Borneo, remarkable for its long tail, two-thirds naked, having the terminal third furnished with a double fringe of long hairs. Its habits are probably similar to those of the Tupaias, of which it may be further noticed that they alone among Insectivora are day-feeders. Family MACROSCELIDTE. Terrestrial Insectivora, with comparatively large brain case, well- developed zygomatic arches, and tympanic bullse ; but the orbits are not encircled by bone, the malar is imperforate, and there are generally no post-orbital processes. The pubic symphysis is long, the tibia and fibula united high up, the metatarsus much longer than the tarsus, the molars broad and quadricuspidate, and the intestinal canalhas a large caecum. These leaping Insectivores are easily distinguished by the great length of their metatarsal bones. All the species are African, and are divisible into two genera : a. i f , c , pm f , TO -| or ; forearm bones united below. Macroscelides. b. i (or - ), c , pm -f, m f ; forearm bones separate. Rhynchocyon. Macroscelides includes ten species widely distributed throughout the African continent. All are closely related, resembling one another in general forms, and even in the colour of the fur. They fall into two groups distinguished by the presence or absence of a small lower fourth molar. M. tctradadylus (fig. 55),. type of the subgenus Petrodromus, differs from all in the absence of the hallux. Of Rhtjnchocyon four closely allied species have been described, all from East Africa. Family ERINACEIDJE. Terrestrial Insectivora, with a small brain case, without post- orbital processes, with slender (rarely imperfect) zygomatic arches, with a short pubic symphysis, and with the tibia and fibula united above. The tympanics are annular, not forming bullne ; the intestine has no caecum ; the penis is carried forwards, and suspended from the wall of the abdomen ; and the upper true molars have each four principal cusps and a small central fifth cusp very characteristic of the family. Subfamily I. Gymtiurinee. Caudal vertebrae numerous ; palate bones completely ossified ; pelvis very narrow ; fur without spines. Gymnura, i f , c |, pm f, m f , with two species, O. rafflcsii and G. suilla, from the Malay Peninsula and Indian Archipelago. The former has the appearance of a large Eat with a long head and projecting mobile snout ; the latter, much smaller, with a short tail and small third upper premolar, has long been known under the name of Hylomys suillus, and classed with the TupaUdx. Both species present a very generalized type of dentition, in this respect occupying an almost central position in the order. v. FIG. 55. Macroscelides (Petrodromus) tetradacty us. x 3. From Peters, Raise nach Mossamlique. Subfamily II. Erinaceinse. Caudal vertebra rudimentary; palate bones with defects of ossification ; pelvis wide ; fur with spines. Erinaceus, i f, c f , pm f, TO f, includes nineteen species (fa miliarly known as Hedgehogs) distributed throughout Europe, Africa, and the greater part of Asia, but they have not been found in Madagascar, Ceylon, Burmah, Siam, the Malay Peninsula and Archipelago, or Australia. All the species resemble one another FIG. 56. Facial parts of Skulls of (A) Erinacevs europxus and (B) E. grayi, much enlarged. Dobson, Proc. Zool. Soc., 1881. closely in the armature of spines which invests the upper surface and side of the body ; and all possess the power of rolling them selves up into the form of a ball protected on all sides by strong spines, the dorsal integument being brought downwards and inwards over the head and tail, so as to include the limbs also, by
the action of special muscles (for description see Monograph of the