SOIURID/E— tamias asiaticds and varieties. 797 



that var. pallidus docs to var. quadrivittatus — a light gray form, in which all 

 the dorsal stripes, except the central one, are nearly obsolete. I have yet to 

 see a specimen in which there are not faint indications of the others. The 

 specimens thus far known are nearly all from the desert region adjoining 

 the Gila River. 



Habitat. — Southwestern New Mexico and adjoining portions of Arizona 

 and Nevada. 



GENERAL REMARKS ON TAMIAS ASIATICUS AND ITS VARIETIES. 



Differential characters. — As already noticed under the head of T. 

 strialus, the present species finds its nearest ally in T. striatus. In size, there 

 is little difference between the larger varieties of T. asiaticus and T. striatus, 

 the latter averaging rather the larger than any form, of the former. The 

 longer tail, different coloration, and presence of two upper premolars in T. 

 asiaticus, as compared with T. strialus, serve at once to distinguish the two 

 species. T. asiaticus differs too widely from either T. lateralis or T. harrisi 

 to render a comparison with them necessary. 



While the five varieties of T. asiaticus above characterized so thoroughly 

 intergrade that they are not to be trenchantly defined, the extreme phases of 

 differentiation are often quite widely diverse, and would require recognition 

 as distinct species were they not found to be so inseparably connected. The 

 extremes of the series in size as in color are vars. pallidus and townsendi, and 

 are developed where the conditions of environment are the most diverse. 

 Specimens from the same locality, of either variety, differ very considerably 

 in color, and sometimes agree quite closely in this respect with the average 

 type from a quite distant region. Thus, occasionally, specimens are met with 

 in the wooded mountainous districts of Colorado that closely approach the 

 pale form of the open arid plains. As will be seen from the subjoined lists 

 of specimens, a considerable portion of the specimens I have had before me 

 are as well referable to one variety as to another. These, as a rule, come 

 from regions intermediate to the localities where the several forms above 

 recognized reach respectively their greatest degree of differentiation. 



Specimens from the northern portions of the continent are almost 

 indistinguishable from others from Siberia. The two examples of the Sibe- 

 rian animal I have had an opportunity of examining correspond in every 

 detail with examples from the Mackenzie River district and other northern 



