32 Mcrriam — Geogrophic Distribution of Life. 



Tlio t'ollowiivj; I)()real goiKa-a of niamnials disappear in tlie 

 Transition Zone • 



Taiuiay * Vulpes * 



Filler f Cervus 



Evotomyp (.)vis * 



Zapus T'rsus * 



Erethizon Xenrotrichns 



A rctomys Condy lura 



The follo\ving Sonuran oenera of niannnals (lisapi)eav in the 

 Transition Zone: 



Antilocapva Perognathus 



Cynomys Bassariscus t 



Sjtilogale J Urocyon j 



Geomys Scalops 

 Thomomys ? 



As ah'eady stated, the only mammalian genus ap]iarently re- 

 stricted to the Transition Zone is Sijna}>f()iiiys — a lennning mouse. 

 A numher of species, however, seem to be nearh^ or quite con- 

 fined to this zone. Among these are the following : 



Sciurus aberti Spermoitliilu.s spilosoma pratensis 

 fossor II grammurus 



carolinensis leucotis townseiidi || 



Taniias merriami Cynomys leucurus 



minimus Sitomys neljrascensis 



pictus boylii 



striatus michiganensis 



Spermophilus olegans Arvifola mogollonensis 

 richardsoni austerus minor 



obsoletus curtatus 



* Except one species, which inliabits a limited part of the .Sonoran 

 Region. 



t Fiber ranges south beyond tlie normai limit of the Transition Zone, 

 but it does so along the banks of cool streams that give it a much lower 

 temperature than that of the surrounding atmosphere. It is probable 

 that both FlhiT ami Cmtor should be classed with aquatic species, the 

 limits of their distril)ution depending on the temperature of the water. 

 The same is true in a less degree of tlie paludal subgenera Xeosorex and 

 Atophyrn.v (of Sorex) and of the semi-amphil )ious members of the subgenus 

 Mijnomcs (of Arvlcola). 



I These genera barely enter the Transition Zone at all except in a very 

 small area in the far West. 



'i Excej)t on higli mountains in the Sonoran IJegiou. 



II Range dow ii into Ujjper Sonoi'au also. 



