orsal side of base.

9. Height of keel 1/7 of length of tip; angle
formed by tip and shaft distinct
_Eutamias alpinus_, p. 616

9'. Height of keel at least 1/5 of length of tip;
angle formed by tip and shaft poorly defined.

10. Height of keel 1/3 of length of tip;
angle formed by tip and shaft 140 deg.
_Eutamias dorsalis_, p. 620

10'. Height of keel 1/5 of length of tip;
angle formed by tip and shaft 130 deg. or
less.

11. Tip more than 29 per cent of length
of shaft. _Eutamias amoenus_, p. 619

11'. Tip less than 28 per cent of length
of shaft. _Eutamias minimus_, p. 617

7'. Base widened and dorsoventrally thickened.
_Eutamias townsendii_, p. 618

5'. Shaft thick; shaft more than .25 mm. in diameter at widest
point.

12. Length of shaft less than 3.00 mm.; length of tip less
than 1.10 mm. _Eutamias quadrivittatus hopiensis_, p. 622

12'. Length of shaft more than 3.10 mm.; length of tip more
than 1.15 mm.

13. Tip less than 28 per cent of length of shaft.
_Eutamias quadrimaculatus_, p. 624

13'. Tip more than 29 per cent of length of shaft.

14. Angle formed by tip and shaft more than 140 deg.;
ridges on either side of tip indistinct.
_Eutamias cinereicollis_, p. 624

14'. Angle formed by tip and shaft less than 135 deg.;
ridges on either side of tip distinct.

15. Shaft less than 3.65 mm. in length, and .55
mm. or less in diameter at widest point.
_Eutamias quadrivittatus quadrivittatus_, p. 621

15'. Shaft usually more than 3.65 mm. in length,
but when shorter, diameter is .60 mm. or more
at widest point.

16. Diameter of shaft at