The transition from this to the next family is effected by two genera, which to such an extent combine the characters of the two as to have led different zoologists to place them sometimes in the one, sometimes in the other. Externally they have all the characters of the Mole-rats of the following family; in the characters of the skull and teeth they more resemble the Voles. The ZOKOR (Siphneus aspalax), which may be taken as an example of these forms, is an inhabitant of the Altai Mountains, has the eyes very small, the external ears reduced to mere rudiments, the body cylindrical, as in the true Mole-rats, and the fore-feet armed with very long and strong claws, of which that on the fifth toe is longer than the toe itself. This animal lives in subterranean runs something like those of the Mole, but of much greater extent, and in burrowing in the earth makes use of its strong incisors to cut through the roots it meets with, and when necessary to loosen the earth. The runs pass very near the surface, and are no doubt made for the purpose of feeding on the tender roots of grasses. A species of Siphneus is said to occur in North China. The other genus (Ellobius) includes two species; one (E. luteus) from the country about the Sea of Aral; the other (E. talpinus) from south-eastern Russia and the west of Asia. The latter abounds in the Crimea. These animals form the sub-family Siphneinæ.
CHAPTER III.
MOLE RATS, POUCHED RATS, POUCHED MICE, JERBOAS, AND OCTODONTIDÆ.
[SPALACIDÆ, OR MOLE RATS]—Characteristics of the Family—Habits—Food—[THE MOLE RAT]—Distribution—Description—[THE CHESTNUT MOLE RAT]—[THE NAKED MOLE RAT]—[THE STRAND MOLE RAT]—Description—Habits—[THE CAPE MOLE RAT]—[GEOMYIDÆ, OR POUCHED RATS]—Characteristics of the Family—The Cheek-pouches—[THE COMMON POCKET GOPHER]—Distribution—Description—Burrowing—Runs—Subterranean Dwelling—[THE NORTHERN POCKET GOPHER]—[HETEROMYINÆ, OR POUCHED MICE]—Difficulties as to Position—Characteristics—[PHILLIPS’ POCKET MOUSE]—Where Found—Description—[THE YELLOW POCKET MOUSE]—[THE LEAST POCKET MOUSE]—[DIPODIDÆ, OR JERBOAS]—Organisation for Jumping—Characteristics—Distribution—[THE AMERICAN JUMPING MOUSE]—Description—Characters peculiar to itself—Habits—[THE TRUE JERBOAS]—Characters—[THE JERBOA]—Distribution—Habits—Mode of Locomotion—[THE ALACTAGA]—[THE CAPE JUMPING HARE]—[THE PORCUPINE-LIKE RODENTS]—[OCTODONTIDÆ]—Characteristics—Sub-Family [CTENODACTYLINÆ]—[THE GUNDI]—[THE DEGU]—Description—Habits—[THE BROWN SCHIZODON]—[THE TUKOTUKO]—[THE CURURO]—[THE ROCK RAT]—Sub-Family, [ECHINOMYINÆ]—[THE COYPU]—One of the Largest Rodents—Description—Burrows—Habits—Mother and Young—[THE HUTIA CONGA]—[THE HUTIA CARABALI]—[THE GROUND RAT].
FAMILY VIII.—SPALACIDÆ (MOLE RATS).
ALTHOUGH the Zokor and its allies in the preceding family have to a certain extent prepared us for the peculiar characters presented by the Mole-rats, these are exhibited by the latter in a much more extreme form. They have a very large broad head, which is usually flattened above, and forms an appropriate anterior termination to a clumsy, cylindrical body, supported upon short stout limbs; their incisor teeth are large and broad, and are most formidably exposed in front of the mouth; their eyes are exceedingly small, hidden in the fur, and sometimes quite rudimentary; the external ears are reduced to the smallest possible size, or altogether wanting; and their tails are either so short as to be concealed within the hair of the hinder part of the body, or altogether wanting externally, although the skeleton still shows some caudal vertebræ. The molar teeth are rooted, and not tuberculate; their surface shows re-entering folds of enamel. The feet have five toes, but the thumb is generally very small, although furnished with a nail. The number of molars varies from three to six on each side in each jaw.
In their mode of life, as in their form and the condition of the organs of sight and hearing, these animals present a considerable resemblance to the Moles; but as their food is exclusively of a vegetable nature, the object of their burrowing is not exactly the same. They all inhabit the eastern hemisphere, and are generally met with in dry sandy plains, the soil of which lends itself readily to mining operations. They seldom quit their burrows, and usually work in these only at night, when they make their way rapidly through the ground, and, like the Mole, can run either backwards or forwards in their subterranean galleries with equal facility. They feed chiefly on roots, and especially on the bulbs and tubers which so many plants possess in the dry districts which they frequent; but some of them also eat nuts, seeds, the young bark of trees, and herbage. None of them fall into a state of torpidity during the winter—indeed, only two species inhabit northern regions; but these, although active in the winter season, are said not to take the precaution to lay up a store of provisions.
SKULL OF MOLE-RAT.
Most zoologists distinguish two groups of Spalacidæ. In the SPALACINÆ, the representatives of which range from south-eastern Europe to further India and the south of China, and also occur in Africa in the countries of Abyssinia and Shoa, the palate between the molar teeth is broader than one of the sockets of the molars, and the angular portion of the lower jaw springs from the lower edge of the bony case of the incisor. To this group belongs the MOLE-RAT (Spalax typhlus), which inhabits Hungary and Galicia, and the south-east of Europe generally, and ranges eastwards into Asia as far as the Caucasus and Ekaterinoslav. It possesses only three molars on each side in each jaw, and has the eyes rudimentary and covered by the skin, so that the animal is quite blind; the upper incisors are placed perpendicularly; and the tail reduced to a sort of wart. The toes, especially those of the fore-feet, are furnished with very powerful claws, which are vigorously employed by the animal in the digging operations above described. The general covering of the body is a soft fur of a yellowish-brown colour, tinged with ashy-grey; the head lighter, but becoming brownish behind; and the lower surface ashy-grey, with some white streaks and spots. The muzzle, chin, and feet are whitish, and along each side of the face there runs a sort of ridge of stiff bristle-like hairs. This species is particularly abundant in the Ukraine and the country about the Volga and the Don.
The genus Rhizomys, of which there are an East Indian and two African species known, has the eyes uncovered, though very small, short naked ears, and a short partially hairy tail. The upper incisors are arched forward. The CHESTNUT MOLE-RAT (Rhizomys badius) lives in Northern India, Siam, and Arracan; and, according to Mr. Finlayson, the food of a specimen in confinement consisted of unhusked rice and other grain, but he showed himself fond of yams and pumpkins. The NAKED MOLE-RAT (Heterocephalus glaber), which has no external ears and a short tail, has the body almost entirely naked. It is a native of Shoa.