COMMON JERBOA. 177 



During the day it commonly remains in its hole ; 

 coming out at night for food and exercise. On 

 the approach of cold it is said to grow torpid for 

 some time, reviving on the change of weather. 



This animal has frequently been brought into 

 Europe, and in a state of confinement has been 

 known to burrow almost through a brick wall. 

 It has been well figured by Edwards, who did not 

 observe any appearance of a spur or back toe. 

 It is possible, however, that from its minuteness it 

 might have escaped his attention. 



The measurements of this species are differ- 

 ently given by authors, anjd it appears clearly 

 to vary somewhat in size bi different countries ; 

 those of Siberia, described by Dr. Pallas, being 

 smaller than those of Africa; and, after all, it is 

 not impossible that they may in reality be distinct, 

 though so nearly resembling each other as to 

 make the distinction very difficult : in Dr. Pallas's 

 specimens a white transvei^se band runs across the 

 upper part of the thighs, whereas in that of Ed- 

 wards a black or dusky band passes across the 

 lower part of the back, without any appearance 

 of the white one It is difficult to determine whe- 

 ther the kind described and figured by Mr. Bruce 

 should be considered as a variety of the present 

 species or of the Alagtaga ; since it agrees with 

 the Common Jerboa, in having the black dorsal 

 band or crescent, while, on the contrary, in the 

 number of its toes on the hind-feet it seems to 

 differ from both ; the author expressly decUiring 



V. TI. p. I. 12 



