_Sigmodon hispidus atratus_ Hall, Proc. Biol. Soc. Washington,
62:149, August 23, 1949, type from 6-1/2 mi. W Zamora,
5,950 ft., MichoacAin.
_Range._--Known only from Zamora and the type locality.
_Specimens examined_, 2: nos. 100628 (the holotype), 6-1/2 mi. W
Zamora, 5,950 ft.; 120268 (U. S. Nat. Mus., Biol. Surveys Coll.),
Zamora.
_Remarks._--When the present account first was prepared our specimen
from six and a half miles west of Zamora was tentatively referred to
_S. h. mascotensis_. Subsequently a second specimen, from Zamora, was
found. It agreed with the specimen from six and a half miles west of
Zamora. Inasmuch as the second specimen agrees with the first and
since each of the two differs from any previously described kind, a
name and description were published in time to be inserted in the
present account. From _S. h. mascotensis_, _S. h. atratus_ differs in
shorter hind foot, darker upper parts, more densely haired tail,
shorter skull, more convex dorsal longitudinal outline of skull,
posteriorly constricted anterior palatine foramina instead of
parallel-sided foramina, and shorter and less decurved anterior
process of maxillary arm of zygoma.
=Neotomodon alstoni alstoni= Merriam