ANIMALS— PHYSICAL ENVIRONMENT 77 



family of rodents, the Muridae, the same modifica- 

 tion of form may be seen in desert species belonging 

 to two of the sub-famiUes. Of the first, the Ger- 

 billinae, or Gerbils ^ (Fig. 33), no member has be- 

 come completely biped, but nearly all the genera 

 and species show some lengthening of the hind-leg 

 and hind-foot and tend to progress at times by 

 running, at others by leaping. The species figured 



Fig. 33. — East African Gerbil {Taterona mcina) from East Africa. 



This animal is typical of a very large number of species, most of which are found in various 

 parts of the Great Palaearctic Desert. (Drawn from life by Miss A. M. Gayton,) 



(Taterona vicina) shows these characteristics well, 

 and is drawn from life in a characteristic biped 

 attitude. Other Gerbils (e.g. Meriones) are more 

 rat-Hke in form and in habit. In the second sub- 

 family, the Murinse or True Mice, occur Conilurus 

 and Notomys in the Australian deserts, exhibiting 

 various stages in the lengthening of legs and feet 



^Examples are Meriones (pages 92, 130, etc.), Gerbillus 

 (page 138), and Dipodillus (pages 103, 127). 



