2. The subgenera _Eutamias_ and _Neotamias_ are valid, for, _Eutamias
sibiricus_ differs from all the species of the subgenus _Neotamias_ to a
greater degree than these species differ from one another.
3. The genera _Eutamias_ and _Tamias_ probably evolved from two distinct
lines of sciurids; one line (_Eutamias_) is represented by the tribe
Callosciurini, and the other (_Tamias_) by the tribe Marmotini.