328 



THE RODENTS OR GNAWING ANIMALS. 



Senses of the All species of this family are en- 

 Jerboas are dowed with acute senses, their hear- 

 Acute. jjig and sight in particular being very 



:good, so that they can easily escape menacing dan- 

 ■gers. Being exceedingly shy, timid and fleet, they 

 try to gain their burrows with all possible speed at 

 the slightest alarm, or, if they cannot do this, they 

 seek safety in flight, proceeding with astonishing 

 •speed. The largest species, if driven to bay, defends 

 itself with its hind legs. Kangaroo-fashion, while the 

 -smaller ones never resort to their natural arms when 

 seized upon. Their voice consists of a kind of 

 whine, resembling the cries of young kittens, though 

 some. utter a hollow grunting noise; but they seldom 

 make any sound. When the temperature is low, 

 they enter into the hibernating state, or at least 

 become torpid for a little while, but they do not lay 

 up a store of provisions, like other Rodents. 



Captive Jerboas make exceedingly agreeable and 

 pretty companions; their good-nature and gentle 

 ■and cheerful disposition render them general favor- 

 ites. 



Nearly all kinds are entirely harmless. The open 

 desert offers them so much provender that they do 

 not make inroads on the property of Man. 



THE JUMPING MOUSE. 



The Jumping Mouse of North America {Jaculus 

 hudsonius) represents a distinct species and sub-fam- 

 ily. Its structure shows an affinity to its Old World 

 relatives, but its shape and the fur of the tail also 

 remind one of a Mouse. Its dimensions are about 

 the same as those of the Wood Mouse; its body is 

 about three inches long, its tail about five inches. 

 The fur is smooth and close, and the color of the 

 upper surface is a dark leather-brown, with an ad- 

 mixture of brownish yellow. 



The Jumping Mouse is indigenous to the higher 

 latitudes of America. It is found throughout the 

 fur-producing region from Missouri to Labrador, 

 and from the Atlantic to the Pacific. It lives on the 

 borders of meadows thickly grown with bushes and 

 in the proximity of forests, and remains hidden by 

 day but roams about with a large band of others of 

 its kind by night. Its burrows are about twenty 

 inches ' deep, and still deeper in the cold season. 

 Before the advent of winter it constructs a hollow 

 ball of clay, rolls itself up in it, curls its tail around 

 its body and lies in perfect lethargy till the begin- 

 ning of spring. A gardener, working out doors in 

 March, is said to have found a lump the size of a 

 child's bouncing ball which astonished him because 

 of its regular shape. When he had split it, in two 

 pieces with his spade, he found a small animal 

 curled up in it, nearly like a Chick in an egg. It 

 was a Jumping Mouse which had taken winter quar- 

 ters in this well enclosed retreat. In summer it is 

 exceedingly nimble and jumps about on its hind 

 legs with extraordinary quickness and agility. It 

 is said to be quite impossible to catch a Jumping 

 Mouse in a forest. It easily clears bushes which a 

 Man cannot readily jump over, and is never at a loss 

 to iind a secure hiding place. Audubon doubts 

 whether there is another mammal which can match 

 it in agility. According to many accounts this 

 pretty little animal can be kept in captivity without 

 any difficulty. 



THE TRUE JERBOAS. 



The True Jerboas {Dipodijice) we regard as types 

 -of the whole family, showing all the peculiarities in 



the most perfect development. Hasselquist aptly 

 remarks that they look as if they were made up 

 from several different animals. "One might say 

 that the little animal had the head of a Hare, the 

 whiskers of a Squirrel, the snout of a Pig, the body 

 and the fore-paws of a Mouse, the hind feet of a 

 bird, and the tail of a Lion." The head is the most 

 prominent feature: one glance at it shows the Jer- 

 boa to be a true inhabitant of the desert. There is 

 ample room for all organs of sense. The ears are 

 large and membranous, and are but scantily covered 

 with hair. The eyes are large and their expression , 

 is mild and full of life, like those of some other noc- 

 turnal animals of the desert; the nostrils are wide, 

 and whiskers of prodigious length surround the head 

 on both sides, duly representing the sense of touch. 

 The neck is exceedingly short and but slightly 

 mobile. The tail is very long, being either a little 

 or much longer than the body.* The portion near 

 the base is round, but the extremity, in most spe- 

 cies, is adorned with a tuft, which is parted in such 

 a way as to resemble an arrow. The fore feet are of 

 small size, and in leaping they are folded against the 

 body and partly hidden in the fur, in a way which 

 justifies the animal's old appellation of "two- 

 footed." The fore-paws have only four toes, armed 

 with moderately long, curved and sharp claws and a 

 rudimentary thumb, which in some species has a 

 nail, and in others none. The hind legs are in some 

 species six times longer than the fore-legs,, gaining 

 these proportions not only because of the elongation 

 of the leg bones, but also from that of the instep or 

 metatarsus. The fur is soft and of silky texture, 

 and on the back the hairs are bluish gray at the 

 base, then sand-colored, and have tips of black or 

 dark brown; the under surface is always white, diver- 

 sified with longitudinal side streaks. It is a remark- 

 able fact that in many swift running animals, and 

 among them the Jerboas, the structure of the feet is 

 of the plainest type and they are but slightly mobile. 

 The jumping feet have three, four or five exceed- 

 ingly short toes, composed, as a rule, of only two 

 joints. The toes are incapable of lateral motion and 

 can only slightly bend downward, simultaneously. 

 In running only the extreme tip of the nail-joint 

 touches the ground, and that is specially protected 

 by a feathered mass of cartilage. 



The Egyptian I select the Egyptian Jerboa {Dipus 

 Jerboa, the Typ- cBgypticus) as the representative of 

 ical Speoies. this species. It is an exceedingly 

 pretty little animal, with a body measuring nearly six 

 inches, while its tail, without the tuft, is nearly eight 

 and one-half inches long. The Jerboas, and' prob- 

 ably this very Egyptian species, were well known to 

 the ancients. We frequently find them mentioned 

 by Greek and Roman authors, always under the 

 appellation of "Two-Footed Mice," this being the 

 origin of the present scientific designation of the 

 species. 



The Jerboa is distributed over the greater part of 

 northeastern Africa, as well as the adjoining part of 

 western Asia. Open, dry plains, steppes and sandy 

 deserts are its habitation. It populates the most 

 arid, deserted regions and lives in localities which 

 barely seem to afford the possibility of an existence. 

 On those dreary plains, covered with hard grass, 

 one occasionally finds it in large cominunities. It 

 shares those spots with the Desert Hen and the 

 little Desert Lark, and other birds, and it is difficult 

 to understand how it can find sustenance in compe- 

 tition with the others, which make but a scanty liv- 



