COMMON JERBOA. 181 



a round shape : it is of a deeper grey above than 

 below, and is furnished with short hair as far as 

 the extremity, which ends in a tuft of long silky 

 hair^ half black and half grey." 



The following is, according to Mons. Sonnini, 

 the average size of the Egyptian Jerboa : it was 

 taken from female specimens, because they hap- 

 pened first to be met with, but M. Sonnini as- 

 sures us, that the difference of size between the 

 sexes is but very slight. 



Length of the body, from the tip of the nose 

 to the origin of the tail, five inches six lines. 



That of the head, measured in a strait line 

 from the tip of the nose to the nape of the neck, 

 one inch eight lines. 



Breadth of the muzzle at its extremity, four 

 lines. That of the opening of the mouth, mea- 

 sured from one angle of the jaw to the other, 

 three lines and a half The upper jaw projects 

 beyond the under three lines and a quarter. 



Length of the upper teeth, two lines : of the 

 under, three. 



Distance between the nostrils, one line : be- 

 tween the tip of the nose and the anterior angle of 

 the eye, ten lines. Between the posterior angle of 

 the eye to the ear, two lines and a half. Between 

 the two angles of the eye, five lines. Distance be- 

 tween the anterior angles of the eyes, measured 

 in a strait line, one inch and half a line. 



Length of the ears, one inch and six lines : 

 breadth of the ears at bottom, live lines. Distance 

 between the ears, nine lines. 



