subgenus _Neotamias_ always differs
from both the subgenus _Eutamias_ and the genus _Tamias_ in pointed
_versus_ rounded pinna of ear (see table 2) and in the supraorbital
notch being slightly posterior to or even with, instead of distinctly
anterior to, the posterior notch of the zygomatic plate. The relative
position of these two notches, however, seems to be a matter of relative
(heterogonic) growth. Further, the base of the postorbital process of
the frontal usually is narrower (relative to the length of the process)
in the subgenus _Neotamias_ but there is a gradation in this feature in
_Neotamias_ culminating in the species _E. townsendii_ in which the
bases of the processes are relatively as broad as in the subgenus
_Eutamias_ and the genus _Tamias_. The same condition obtains in the
shape of the infraorbital foramen which is subovate to rounded in the
subgenus _Neotamias_ and always rounded in the other chipmunks.

TABLE 2.--CHARACTERS BY MEANS OF WHICH THE SUBGENUS EUTAMIAS AND THE
GENUS TAMIAS MAY BE DISTINGUISHED FROM THE SUBGENUS NEOTAMIAS

========================================================================
Character | subgenus | subgenus | genus
| _Neotamias_ | _Eutamias_ | _Tamias_
-------------------------------+--------------+-------------+-----------
Shape of infraorbital foramen. | subovate to | always | always
| rounded. | rounded. | rounded.
-------------------------------+--------------+-------------+-----------
Relative width of the | narrow to | |
postorbital process at base. | broad. | broad. | broad.
-------------------------------+--------------+-------------+-----------
Position of supraorbital notch | even with or | |
in relation to posterior | slightly | anterior. | anterior.
notch of zygomatic plate. | posterior. | |
-------------------------------+--------------+-------------+-----------
Convergence, posteriorly, | not always. | not always. | always.
of upper tooth-rows. | | |
-------------------------------+--------------+-------------+-----------
Degree of constriction of | slight | marked. | marked.
interorbital region. | to marked. | |
-------------------------------+--------------+-------------+-----------
Shape of pin