^xpfste.} LIFE HISTORY OF THE KANGAROO EAT. 15 



Occasionally a bold individual is found, as in the case of one which 

 came out repeatedly, even after being flashed twice in the same nighi. 



Certain peculiar physical characteristics suggest a relationship lo 

 sense reactions. On these, however, the authors are not prepared to do 

 more than offer suggestions for future work. The extremely large 

 mastoids found in kangaroo rats suggest a connection in some way 

 with special developments of the sense of hearing or of balance. It 

 may be noted that an intermediate condition between the kangaroo 

 rats and the majority of rodents in respect to this character is to 

 be found in the pocket mice (Perognathus), which belong to the 

 same f amil}'. Herein lies a field for some interesting experimentation 

 and discovery. 



The small, pointed nose might suggest a not overkeen sense of 

 smell, and there appears no reason to believe that this sense is par- 

 ticularly well developed. However, the turbinals are very complex. 

 The vibrissse are long and sensitive, and may indicate a special devel- 

 opment of the sense of touch as an adaptation to nocturnal habits 

 and to life in an underground labyrinth. The long, well-haired tail 

 doubtless serves as an important tactile organ as well as a balance. 



MOVEMENTS AND ATTITUDES. 



Movements and attitudes are characteristic. As a kangaroo rat 

 emerges from the burrow a reason for the relatively large size of the 

 opening is seen in the fact that, kangaroolike, the animal maintains 

 a partially upright position. Its ordinary mode of progression is 

 hopping along on the large hind legs, or, when in the open and going 

 at speed, leaping. When moving slowly about over the mound, as 

 if searching for food, it uses the fore legs in a kind of creeping move- 

 ment. It appears to be creeping when pocketing grain strewn about, 

 but close observation shows that the fore feet are then used for sweep- 

 ing material into the pockets, reminding one somewhat of a vacuum 

 cleaner. When it assumes a partially upright position the fore limbs 

 are usually drawn up so closely that they can be seen only by look- 

 ing upward from a somewhat lower level than that occupied by the 

 animal. The slower movements of searching or playing about the 

 mound are occasionally interrupted by a sudden leap directly upward 

 to a height of 1^ to 2 feet, often with no apparent reason other than 

 plaj'. This is, however, a fighting or guarding movemem;, though 

 indulged in for play. The play instinct seems to be well developed, 

 and in evidence on anj- moonlight night when actual harA'esting oper- 

 ations are not going on. 



STORING HABITS. 



Probably no instinct is of greater importance to the kangaroo rat 

 than that of storing food supplies. When a crop of desirable seeds 



