he genus (see
measurements); tail medium in length, sparsely covered with
whitish hairs; claws of forefeet slender; upper parts near
(h) Buffy Brown (capitalized color terms after Ridgway,
Color Standards and Color Nomenclature, Washington, D. C.,
1912), with slight rufous wash on top of head; underparts
resemble upper parts but slightly paler with longitudinal
band of near (14) Sudan Brown extending from chin
posteriorly to and around base of tail, less intense on
breast; skull small, arched, and relatively slender
especially across mastoidal region; posterior part of
cranium depressed; foramen magnum low when viewed from rear;
external pterygoid region not greatly expanded; teeth small,
especially upper third molar.

_Comparison._--From _Scalopus aquaticus_, of which ten
subspecies have been seen including those of significant
geographic position, _S. montanus_ differs in: Skull
slenderer, less angular and relatively narrower across
mastoidal region; cranium arched with hind part flattened;
external pterygoid region less expanded; teeth relatively
small, especially last upper molar. From _S. inflatus_,
known to me from Jackson's description (N. Amer. Fauna,
38:53-54, pls. 2, 3, September 30, 1915), _S. montanus_
differs in: Skull less angular and slenderer, prelachrymal
region not inflated; zygomata slenderer.

_Remarks._--_S. montanus_ is known from a single specimen, which
represents the second known occurrence of the genus _Scalopus_ in
Mexico. The other occurrence is that of _S. inflatus_ in the state of
Tamaulipas. _S. montanus_ is geographically isolated in mountainous
country from other species of _Scalopus_. Ten of the recognized
subspecies of _S. aquaticus_ were available for examination and
descriptions of others were studied. It was found that the number and
magnitude of the differences separating any one of these subspecies
from an adjoining one was less than those separating _S. montanus_ from
_S. a. texanus_ and _S. a. intermedius_, which are, geographically,
closest to _S. montanus_. _S. montanus_ seems not to be closely related
to _S. inflatus_ of Tamaulipas. _S. montanus_ is given specific rank
because of the great degree of difference between it and its nearest
relatives, and because of its geographically isolated position.

The specimen of _S. montanus_ was taken in a tunnel f