4 



BULLETIlSr 1091, V. S. DEPARTMENT OF AGRICULTURE. { buIi^'n!)^.'^!, 



lack tlie conspicuous white liip stripe x^ossessed by all the latter; and 

 (g) the kangaroo rats (Dipodomys) . 



Dijjodomys syectabilis SfectahUis Merriam requires comparison 

 with three other forms of kangaroo rats in the same general re- 

 gion, namely, D. deserti Stephens, of approximately the same size, 

 and D. merriami Mearns and D. ord'd Woodhouse, the last two of 

 decidedly smaller size. The range of deserti lies principally to the 



east of The Co/orado /?/ ver 

 1 1 1 1 1 [ II Di podorriLfs 

 Spectobi/i's specf-ab/'/'s 



Fig. 1. — Range, east of tbe Colorado River, of Uiitirdomyft speetahilis spectahUh com- 

 pared with that of Dipodomys merriami. Cross hatching indicates area of overlapping 

 of the two forms. The range of Dipodomys deserti, not shown on tlie map, is west of i 

 that of spectaMHs, and so far as Isnown the two do not overlap. 



west of that of HpectcdAllH. and the two do not, so far as known, over- 

 lap. On the other hand, merriami ^ndordii^ and subspecies, occur over 

 a large part of the range of speetdbilis,, living in very close proximity 

 to its burrows ; 'tnerriami is even suspected of pillaging the stores of 

 spectaljilis. The range of merricmii, however, is much more exten- 

 sive than that of spectaljilis (Fig. 1), which argues against a definite 

 ecological dependence or relationship. Separation of the four forms i 

 mentioned maj' be easily accomplished by the following key : 



