1. Distal 1/2 to 2/3 of shaft markedly compressed laterally; base
markedly widened.
2. Distal 1/2 of shaft laterally compressed and curved downward
to base of tip.
3. Height of keel 1/2 of length of tip; keel markedly
enlarged. _Eutamias bulleri_, p. 627
3'. Height of keel 1/4 of length of tip; keel not markedly
enlarged.
_Eutamias umbrinus_ and _E. palmeri_, pp. 626, 627
2'. Distal 2/3 of shaft laterally compressed and curved downward
to base of tip.
4. Base of keel 1/3 of length of tip; angle formed by tip
and shaft less than 100 deg. _Eutamias speciosus_, p. 625
4'. Base of keel 1/2 of length of tip; angle formed by tip
and shaft more than 102 deg. _Eutamias panamintinus_, p. 625
1'. Distal 1/12 to 2/5 of shaft slightly compressed laterally; base
not markedly widened.
5. Shaft thin; shaft less than .20 mm. in diameter at widest
point.
6. Ridges on either side of keel enlarged, partially
obscuring lateral view of keel; height of keel 1/10 of
length of tip. _Eutamias sonomae_, p. 619
6'. Ridges on either side of tip not enlarged, not partially
obscuring lateral view of keel; height of keel at least
1/7 of length of tip.