er.

Summer molt begins, topographically, in the region of the head and
progresses posteriorly to the base of the tail, for, the tail does not
molt into summer pelage. The winter molt starts at the same time at the
tip of the tail and at the base of the tail, and from each place
proceeds anteriorly. The sequence described above is the rule;
exceptionally, there are some specimens which molted in patches. In
most skins, molts are easily detected because distinct molt-lines were
formed. The above description of molting is based on study of a large
series of specimens of _Eutamias minimus silvaticus_ taken in several
seasons of the year.

The summer pelage is bright, more especially on the sides. In late
summer the pelage on the tail is markedly worn, and the hairs around
its outer margin are broken. In texture, the summer pelage is not so
soft as winter pelage, and this is probably owing to the presence of
large amounts of "kinky" underfur in the winter pelage.

The winter pelage is soft, dull in color, and gives the specimen a
grayish or an umbrous appearance. The guard hairs are longer than in
the summer pelage.

KEY TO THE SPECIES OF THE CHIPMUNKS OF WYOMING

1. Dorsal stripes faint; general tone of upper parts grayish.
_Eutamias dorsalis_, p. 603

1'. Dorsal stripes distinct; general tone of upper parts tawny (not
grayish).

2. Venter yellowish or buff; tip of baculum more than 30 per
cent of length of shaft; shaft of baculum not widened at base.
_Eutamias amoenus_, p. 602

2'. Venter white; tip of baculum less than 29 per cent of
length of shaft--if more than 29 per cent, shaft widened at
base.

3. Size small to medium; greatest length of skull less
than 34 mm.; shaft of baculum not widened at base;
outermost dorsal dark stripe never obsolete _Eutamias
minimus_, p. 590

3'. Size large; greatest length of skull rarely less than
34 mm.; shaft of baculum widened at base; outermost dorsal
dark stripe often obsolete, never strongly evident.
_Eutamias umbrinus_, p. 606

ACCOUNTS OF SPECIES AND SUBSPECIES

Eutamias minimus (Bachman)

_Diagnosis._--Size small; tip of baculum of adults less than 28 per
cent of length of shaft; outermost dorsal dark stripes distinct;
skull small to medium; when skull medium, zygomatic breadth not