than
_crawfordi_ but a relatively (sometimes actually) shorter tail and ear,
and a distinctly larger, heavier skull (see Table 1). The upper parts of
our specimens average pale brownish gray and are paler, not darker, than
the upper parts of _crawfordi_. But, all of the latter were obtained in
the warm months of the year except one November-taken individual from El
Fuerte, Sinaloa, the dorsal pelage of which approaches in color that of
the darkest of the _evotis_. The pelage of both kinds probably is paler
in winter than in summer and may be indistinguishable in the same
season. Ventrally, all four _evotis_ are grayish white, faintly to
moderately tinged with brownish buff.

_Notiosorex evotis_ differs cranially from _Notiosorex crawfordi_ as
follows: larger (see measurements); mesopterygoid fossa squared rather
than broadly U-shaped anteriorly; rounded process on maxillary at
posterior border of infraorbital canal well developed (faint or lacking
in _crawfordi_); occipital condyles smaller and, in lateral view,
elevated above basal plane of skull; upper molars slightly more crowded
in occlusal view. These differences, although admittedly slight, appear
to be constant in the specimens we have seen, but ought to be used
cautiously owing to the small samples studied.

Shrews of the genus _Notiosorex_ have been reported twice previously
from localities in west-central M['e]xico, other than from Mazatl['a]n, as
follows: 21 mi. SW Guadalajara (remains from owl pellets) and 13 mi. S,
15 mi. W Guadalajara, Jalisco, by Twente and Baker (1951:120-121); and
Cerrito Loco, 2 mi. E La Palma, Michoac['a]n (remains from owl pellets), by
Baker and Alcorn (1953:116). The remains were referred to _evotis_ on
geographic grounds in one instance and were so referred inferentially in
the other. Examination of the specimens upon which these reports were
based reveals that all are _crawfordi_ on the basis of characters
previously cited. As a result, _N. evotis_ is known only from the type
locality at Mazatl['a]n, whereas _N. crawfordi_ is widely distributed on
the Mexican Plateau as far south as Jalisco and northern Michoac['a]n, and
occurs on the west side of the Sierra Occidental as far south as
northern Sinaloa.

The two kinds obviously are closely related and intergradation
eventually may be demonstrated between them. But, for the present, we
adopt a conservative course and treat _evotis_ as a full species owing
to its distinctive feat