178 COMMON JERBOA. 



that there are four toes forwards, exclusive of a 

 very short one or spur behind. 



Mons. Sonnini, in his Egyptian travels, assures 

 us, that he never was able to find any difference 

 either in the form or colour of the Egyptian Jer- 

 boa. Mons. Sonnini considers the Jerboa as con- 

 stituting a link between quadrupeds and birds. 

 In this idea he is by no means singular ; the same 

 sentiment naturally suggesting itself to the mind 

 of every philosophical observer. Mons. Sonnini 

 adds, that though the transition from quadrupeds 

 to birds has not yet been investigated, we have 

 nevertheless reason to consider the connexion as 

 existing. We have the beginning of it in the 

 Jerboa, and the last link of it in the Bat. We have 

 every reason to believe, that the series of grada- 

 tions will develope itself in proportion as good 

 observers shall carry their researches into coun- 

 tries the natural history of which is still unex- 

 plored *. 



M. Sonnini describes the Egyptian Jerboa as 

 follows : 



" Its size is nearly equal to that of a large rat : 

 its head is broad, large in proportion to the body, 

 the upper part flat, and of a light fawn-colour, 

 striped with black : the upper jaw projects beyond 

 the lower : they are both provided with two in- 

 cisores ; the upper ones broad, square, flat, and 



* The Platypus or Duck-Bill, from New Holland, is a striking 

 instance of the truth of this remark. 



