wnish above and white below. Skull small; tympanic
bullae small; rostrum wide; skull indistinguishable from
that of _P. f. flavescens_ from the same latitude in western
Kansas.

_Comparisons._--_Perognathus flavescens cockrumi_ averages
approximately 12 per cent smaller in linear measurements
than the more northern _Perognathus flavescens perniger_
Osgood (from Knox, Stanton and Cumming counties, Nebraska)
but color of upper parts is essentially the same. From the
more western _Perognathus flavescens flavescens_ Merriam
(from Seward, Hamilton and Morton counties, Kansas),
_cockrumi_ differs in being darker in all parts of the
pelage except on the underparts which are white in both
subspecies; the parts of the hairs that are Ochraceous-Buff
in _cockrumi_ are Light Ochraceous-Buff in _flavescens_; the
back of _cockrumi_ is blackish instead of yellowish. From
the more southern _Perognathus flavescens copei_ Rhoads
(topotypes examined but not at hand as I write), _cockrumi_
differs in duller more blackish (less bright and less
reddish) upper parts. From _Perognathus merriami gilvus_, of
more southern distribution, the new subspecies differs in
much smaller tympanic bullae and wider rostrum.

_Measurements._--The type, a male (35331/47596 U.S.B.S.,
from Cairo, Kansas, showing some wear on P4), and another
male (60165 K. U., from Barber Co., Kansas, showing much
wear on P4) measure, respectively: Total length, 114, 120,
124; tail, 51, 55, 58; hind foot, 17, 17, 18; occipitonasal
length, ----, 21.0, 21.6; condylobasal length (condyles to
anterior end of premaxillae), 18.5, 18.6, 19.3; frontonasal
length, ----, 14.1, 14.3; mastoidal breadth, 10.5, 11.2,
11.2; length of bulla, 6.8, 7.1, 6.8; interorbital breadth,
4.7, 4.8, 5.1; alveolar length of upper molariform
tooth-row, 3.1, 3.1, 3.0; interparietal breadth, 4.3. 4.6,
4.7.

_Remarks._--The subspecific name _cockrumi_ is proposed in recognition
of Dr. E. Lendell Cockrum's important contribution to our knowledge of
the mammals of Kansas. Dr. W. Frank Blair recently suggested to me that
the two specimens examined by him from Kansas (the one from Ellsworth
County and the one here designated as holotype) should not be referred
to _Perognathus flavescens copei_ Rhoads, as Cockrum (Univ. Kansas
Publ., Mus. Nat. His