120 NATURAL HISTORY. 



two are found in North America, the last also in Greenland. In this species, which has been 

 placed in a distinct genus under the name of Cuniculus torquatus, the third and fourth toes of the 

 fore feet are much larger than the second and fifth (the thumb being rudimentary), and their claws 

 become periodically enlarged to double their ordinary size by an enormous growth during winter 

 of horny matter on the lower surface. 



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 

 follow ing 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 (Ettobius) 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 Siphneinae. 



CHAPTER III. 



MOLE RATS, POUCHED RATS, POUCHED MICE, JERBOAS, AND OCTODONTID^E. 



SPALACID./E, OR MOLE RATS Characteristics of the Family Habits Food THE MOLE RAT Distribution Descrip- 

 tion THE CHESTNUT MOLE RAT THE NAKED MOLE RAT THE STRAND MOLE RAT Description Habits THE 

 CAPE MOLE RAT GEOMYID^E, OR POUCHED RATS Characteristics of the Family The Cheek-pouches THE 

 COMMON POCKET GOPHER Distribution Description Burrowing Runs Subterranean Dwelling THE NORTHERN 

 POCKET GOPHER HETEROMYINJE, OR POUCHED MICE Difficulties as to Position Characteristics PHILLIPS' 

 POCKET MOUSE "Where Found -Description THE YELLOW POCKET MOUSE THE LEAST POCKET MOUSE DIPO- 

 DID^E, 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 

 OCTODONTIDJ2 Characteristics Sub-Family, CTENODACTYLIN^E THE GUNDI THE DEGU Description Habits 

 THE BROWN SCHIZODON THE TUKOTUKO THE CURURO THE ROCK RAT Sub-Family, ECHINOMYIN.E THE COYPU 

 One of the Largest Rodents Description Burrows Habits Mother and Young THE HUTIA CONGA THE 

 HUTIA CARABALI THE GROUND RAT. 



FAMILY VIII. SPALACID^E (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 

 ai-e 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 vertebrae. 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 considei'able 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 



