TJie Chipmit}>l:'< of tlir Or}ivi< Eiifamias. 191 



latitude 44° and latitude 45°, and is then replaced ])y PJ. senex, 

 which ranges thence southerly to the headwaters of the Merced, 

 a little south of latitude 38°. 



But it is in the Sierra Nevada of California that the genus Eu- 

 tdiiilds reaches its most extraordinary develoi)ment. On l)oth 

 slopes of this lofty range species of Chipmunks are distributed 

 in belts, one above the other, corresponding with the strongly 

 marked life zones of the slopes. In most parts of the Sierra two 

 species occur together, in some localities three, and in a small 

 area near timber-line in the Yosemite National Park probably 

 four. Since in following the Sierra northward the Boreal zones 

 come lower and lower down, so certain Chipmunks which in the 

 southern part are found only at high altitudes descend in the 

 north till they reach base level at the upper end of the Sacra- 

 mento Valle3^ 



In crossing the High Sierra between Owens Valley and Fresno 

 one traverses in a distance of only 50 miles the ranges of at least 

 seven very distinct Chipmunks, as follows : On beginning the 

 climb in Owens Valley one finds in the sage-brush the ordinary 

 Great Basin species, E, pictus ; a little higher up, in the nut pine 

 belt, the most beautiful species of the genus, E. panninintinus. 

 Then on entering the Boreal Zone he encounters two very dis- 

 tinct species, E. amcenus and E. speciosiis. Still higher, in the 

 neighborhood of timber-line, he sees for the first time the little 

 Alpine Chipmunk, E. alpinus, and a little farther north the large 

 E. senex.'-^ On descending the west slo})e he passes through the 

 zone inhal)ited by E. callipeplas, a strikingly beautiful member 

 of the speciosus group, and on the lower slo|)e enters the belt in 

 which E. merriami is the sole representative of the genus. If the 

 section were made as far north as the Yosemite National Park, 

 two others would be added, E. senex, along tlie. summit of the 

 range, and the superb E. quadriviaculatus, at lower altitudes on 

 the west slope. 



A good deal of work remains to be done in determining the 

 exact boundaries of the areas inhabited by each species, but 

 enough is already known to show that the group j)resents some 

 very interesting peculiarities of distribution. For instance, Eu- 

 tamias alpinus is distinctly an animal of the Iludsonian Zone of 



* Whether or not E. alpinus and senex actually occur together is not 

 known. E. amrmus M^as not collected bj^ the Death Valley Expedition 

 south of Independence Creek. 



