colour and length of the fur. Their general appearance is very Squirrel-like. Their food consists of insects and fruit, which they usually seek 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.-Represented only by the Pentailed Tree-Shrew (P. lowi, Fig. 283) of Borneo, in which the tail is of extraordinary length, with the proximal two-thirds naked, and the remaining third furnished with a bilateral fringe of long hairs, from which the genus takes its name.

Extinct Genera.-An Insectivore from the Middle Miocene of France, described as Lantanotherium, is said to be nearly allied to Tupaia. The genus Parasorex, from strata of similar age, has the dental formula i 3, c 1, p 4, m 3, and is regarded as connecting the present with the following family.

Family MACROSCELIDIDE.

Skull with comparatively, large brain-case, strong zygomatic arch, a tympanic bulla, orbit surrounded by bone, imperforate jugal, and usually no postorbital process. Molars broad, with

four cusps arranged in a W. Pubic symphysis long; proximal end of tibia and fibula united; radius and ulna united or separate ; metatarsus much longer than tarsus. A large cæcum. Habits terrestrial, saltatorial, and nocturnal. The family is confined to Africa.

Macroscelides.2-Dentition: i, c, pi, m2; total 40 or 42. Distal extremity of radius and ulna united. Five digits in manus, and five or four in pes. This genus, which is taken to include Petrodromus, comprises ten species widely distributed throughout the African continent. All are closely related, resembling one another in general form, and even in the colour of the fur. They fall into two groups, distinguished by the presence or absence of a small third lower molar.3 M. tetradactylus (Fig. 284), the type of the genus Petrodromus, differs from all the other species in the absence of the hallux, and of the third lower molar. These animals are commonly known as Jumping Shrews, and, like the following genus, have the muzzle much produced.

Rhynchocyon.-Dentition: i, c 1, p 4, m; total 36. Upper incisor frequently shed in the adult. Radius and ulna distinct;

1 Gray, Proc. Zool. Soc. 1848, p. 23. 2 Andrew Smith, S. African Quart. Journ. vol. ii. No. 1, p. 64 (1833).

3 The above correct formula of the dentition of this family has been recently worked out by O. Thomas, Proc. Zool. Soc. 1890, pp. 445, 446.

* Peters, Bericht k. preuss. Ak. Wiss. 1847, p. 36.

hind limbs relatively shorter, and proboscis longer than in the type Four closely allied species have The head and body of the type

genus; four digits in each foot. been described from East Africa.

FIG. 234.-Macroscelides tetradactylus. x. (From Peters, Reise nach Mossambique.) species measures about 8 inches in length; and the long tail is covered with a ringed skin, sparsely haired. Its habits are fossorial.

Family ERINACEIDE.

Skull with a small brain-case; no postorbital process; slender and occasionally imperfect zygomatic arch, and an annular tympanic, which does not form a bulla. Upper molars with four principal cusps and a small central median cusp. Acromion of scapula bifid; pubic symphysis short; radius and ulna free, but tibia and fibula united proximally. No cæcum; penis carried forward and suspended from the wall of the abdomen. Habits terrestrial. Found in the Palæarctic, Ethiopian, and Oriental regions.

Subfamily Gymnurinæ.-Palate completely ossified; pelvis very narrow; fur without spines.

Gymnura.-Dentition: i, c1, p 4, m; total 44. This genus, if Hylomys is rightly included, is represented by the two 1 Horsfield and Vigors, Zool. Journ. vol. iii. p. 246 (1828).

species, G. rafflesi and G. suilla, from the Malay Penisula and Indian Archipelago. The former has the appearance of a large Rat with a long tail and head and projecting mobile snout; the latter, which is 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 Tupaida. Both species present a very generalised type of dentition, in this respect occupying an almost central position in the order. G. suilla is represented in Mount Kina-Balu, Borneo, by a variety characterised by the presence of a dark dorsal streak. Many zoologists prefer to retain Hylomys as a distinct genus.

Subfamily Erinaceinæ.-Palate imperfectly ossified; pelvis wide; fur with spines.

Erinaceus.-Dentition: i, c, p3, m; total 36. The first pair of upper incisors (Fig. 285) are considerably larger than the others,

FIG. 285.-Right lateral aspect of the anterior portion of the skull of the Hedgehog (Erinaceus europaeus). Enlarged. (From

Dobson, Proc. Zool. Soc. 1881, p. 403.)

and are widely separated from one another in the middle line; the canine is very similar to the third incisor; and, except in E. europaeus (Fig. 285), each of these teeth is inserted by two distinct roots (Fig. 280, p. 610). The first lower incisor is large and proclivous.

number of vertebræ is C 7, D 15, L 6, S 3, C 11.

The

The Hedgehogs comprise nearly twenty species, distributed throughout Europe, Africa, and the greater part of Asia, but not found in Madagascar, Ceylon, Burma, Siam, the Malay Peninsula, or Australia. All the species resemble one another in the armature of spines investing the upper surface and sides of the body; and all possess the power of rolling themselves up into the form of a ball, protected on all sides by the 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. The common Hedghog (E. europaeus) is the most aberrant species, differing from all the rest in the peculiarly shaped and single-rooted third upper incisor and canine (Fig. 285), and in its very coarse, harsh fur. The dentition of the long-eared North Indian form, E. collaris (Fig. 280), may be considered characteristic of all the other species, the only important differences being found 1 Linn. Syst. Nat. 12th ed. vol. i. p. 75 (1766).

in the variable size and position of the second upper premolar, which is very small, external, and deciduous in the Indian E. micropus and pictus. The former species, limited to South India, is further distinguished by the absence of the jugal bone. Of the African species, E. diadematus, with long frontal spines, is probably the commonest; while E. albiventris has been made the type of a separate genus on account of the total absence of the hallux.

The well-known European species feeds on insects, worms, slugs, mice, rats, lizards, snakes, etc., as well as on eggs, fruit, and roots. It hibernates during the winter. The young are usually produced in July or August in litters of not more than four, but there may be a second litter in October; and the period of gestation is believed not to exceed a month. The Indian, and probably also the African species, do not hibernate.

The existing E. europaeus dates from the Pleistocene period, and extinct species of the genus are found in the Upper and Middle Miocene of the Continent.

Extinct Genera.-The French Lower Miocene genus, Palæoerinaceus, appears to be allied to Erinaceus, but is distinguished by the wider and completely ossified palate. In the Upper Eocene of Central France there are two genera, which appear to be most nearly allied to Gymnura, although connected by Palæoerinaceus with Erinaceus. Of these Necrogymnurus,1 with which Cayluxotherium is apparently identical, has teeth like Gymnura, but an imperfectly ossified palate like Erinaceus; and the skull is remarkable for the peculiar rugose structure of the parietal and temporal regions. Comphotherium is distinguished by the presence of a cingulum to the lower molars, like that found in Gymnura.

Family SORICIDÆ.

Skull (Fig. 286) long and narrow, with no zygomatic arch or postorbital process, and the tympanic ring-like and not forming a bulla. Upper molars with the cusps arranged in a distinct W. No pubic symphysis. The tibia and fibula united. No cæcum. Habits usually terrestrial, rarely aquatic. Distribution extensive.

The Shrews are Rat-like or Mouse-like insectivores, with the body covered with hair, and the muzzle long and pointed. Their dentition (Fig. 286) is peculiar and characteristic. Thus the first upper incisor is large and hook-like, with a more or less developed basal cusp on the posterior border. Between this and the last premolar there are a variable number of small teeth, representing the other incisors, the canine, and the anterior premolars; although, owing to the early obliteration of the maxillo-premaxillary suture,

1 Originally given incorrectly as Neurogymnurus.

their homology is exceedingly difficult to determine. Three molars are invariably present, of which the third is much the smallest. In the mandible there are always six teeth, but in one species of

cpm

FIG. 286. — Left lateral view of the cranium and mandible of Sorex vero pacis,

In the cranium-i, first incisor; c, fourth

Myosorex there may be a seventh. The first lower incisor is usually directed horizontally forwards; the second incisor (formerly reckoned as the canine) is the smallest tooth of the series, the fourth premolar being slightly larger.

This family, which includes considerably more than half the representatives of the order, has distribution coextensive with the latter. Many classifications of this difficult group have been attempted, but according to the latest proposal of Dr. Dobson,1 the genera may be divided into two subfamilies, distinguished by the apparently trivial character of the colour of the teeth. Subfamily Soricinæ.-Summits of the teeth coloured red. Sorex.2-Dentition: i, c, p, m; total 32. Openings of male and female generative organs separated from the anal orifice; penis cylindrical or tapering; ear well developed; tail long, covered with equal or subequal hairs.

incisor; p, canine; m, fourth premolar: in the mandible-i, first incisor; c, second incisor; p, fourth premolar; m, first molar. (From Alston, Proc. Zool. Soc. 1877.)

It has been shown by Brandt that the position of the premaxillo-maxillary sutures in the type of the genus is between the fourth and fifth tooth, so that it appears that we must regard this genus as differing from all other Eutherian mammals in having four upper incisors. Dr. Dobson, in his paper quoted, classes the tooth here reckoned as the upper canine with the premolar series in all the Shrews. Habits terrestrial. Species numerous, inhabiting the Palearctic and Nearctic regions.

Of the two species found in the British Isles the Common Shrew (S. vulgaris, Fig. 287) is by far the most common in England, and is about the size of the House Mouse, to which it approximates in general form. The body is clothed with close long fur, very soft and dense, and varying in colour from light reddish to dark brown above, rarely speckled or banded with white. The under surface of both the body and the tail is grayish. The basal fourfifths of all the hairs above and beneath are dark bluish-gray; the hairs of the tail are less densely set and coarser. On each side of the body, at a point about one-third of the distance between the elbow and the knee, may be found, especially in the rutting season, 1 Proc. Zool. Soc. 1890, p. 49. 2 Linn. Syst. Nat. 12th ed. vol. i. p. 73 (1766).