Tlaxcala. Thomas (1903)
described from Orizaba, Veracruz, _P. beatae_, which Osgood (1909)
mistakenly thought was indistinguishable from _P. boylii levipes_.
Therefore, Osgood in 1909 in his revision of the genus _Peromyscus_
reported only two subspecies of _P. boylii_ from eastern Mexico: _P. b.
levipes_, and _P. b. aztecus_. Study of Osgood's and Thomas' material,
along with recently collected specimens from the states of eastern
Mexico, leads me to conclude that _P. aztecus_ and _P. boylii_ are
different species; that _P. beatae_ is a valid subspecies different from
_P. b. levipes_; and finally that specimens of _P. boylii_ from Nuevo
Leon and northwestern Tamaulipas pertain to an hitherto unnamed
subspecies.

#Peromyscus aztecus# Saussure

1860. _H[esperomys]. aztecus_ Saussure, Revue et Mag. Zool.,
Paris, ser. 2, 12:105, type from southern Mexico, probably
from the vicinity of Mirador, Veracruz, according to Osgood
(N. Amer. Fauna, 28:156-157, April 17, 1909).

1909. _Peromyscus boylei aztecus_, Osgood, N. Amer. Fauna,
28:156, April 17.

_Geographic distribution._--Known only from Mirador and Jalapa
in Veracruz, and Huachinango in Puebla.

_Diagnosis._--Size medium for the genus (see measurements); tail
about as long as head and body; dorsal coloration near Sayal
Brown (capitalized color terms after Ridgway, 1912); sides
reddish; underparts Light Buff; tail bicolored but not
distinctly so; supraorbital border of skull angular, and bullae
pointed anteriorly; anterior half of braincase nearly straight
(not rounded) as viewed from above; upper molar series long
(4.7-5.0); incisive foramina short in relation to length of
skull.

_Comparisons._--From _Peromyscus boylii_, _P. aztecus_ differs
as follows: Larger in most parts measured; maxillary tooth-row
4.7-5.0 instead of 4.0-4.6; color brighter on sides (reddish
instead of ochraceous); supraorbital border angular instead of
rounded; anterior border of zygomatic plate convex in upper half
and almost straight in lower half as opposed to nearly straight
throughout in _boylii_; pterygoid fossa broader; bullae more
pointed anteriorly and less inflated; mesostyles of upper molars
larger; surface between orbital region and nasals convex in
lateral view instead of flat.

_Remarks._--When Saussure (1860:105) described _P. aztecus_ he did not
d