Table 2.—Characters by Means of Which the Subgenus Eutamias and the Genus Tamias May Be Distinguished from the Subgenus Neotamias
| Character | subgenus Neotamias | subgenus Eutamias | genus Tamias |
| Shape of infraorbital foramen. | subovate to rounded. | always rounded. | always rounded. |
| Relative width of the postorbital process at base. | narrow to broad. | broad. | broad. |
| Position of supraorbital notch in relation to posterior notch of zygomatic plate. | even with or slightly posterior. | anterior. | anterior. |
| Convergence, posteriorly, of upper tooth-rows. | not always. | not always. | always. |
| Degree of constriction of interorbital region. | slight to marked. | marked. | marked. |
| Shape of pinna. | long and pointed. | broad and rounded. | broad and rounded. |
These differences of Neotamias are so slight in comparison with the similarities (ten features mentioned above) that Neotamias here is accorded only subgeneric rank under the genus Eutamias, instead of generic rank.
Howell’s (1929) arrangement of the genera and subgenera of chipmunks is judged to be correct as indicated by the following arrangement that I propose.