_Sigmodon melanotis_ Bailey, Proc. Biol. Soc. Washington, 15:114, June 2, 1902, type from Patzcuaro, 7,000 ft., Michoacan.

_Range._--Central Michoacan, as now known.

_Specimens examined_, 8: nos. 100623-100626, 52089-52092, distributed by localities as follows: 2 mi. W Patzcuaro (7,400 and 7,700 ft.), 2; 3-1/2 mi. S Patzcuaro, 7,800 ft., 2; Tancitaro, 6,000 ft., 4.

_Remarks._--This species was taken along with the species _S.

hispidus_ two miles west of Patzcuaro, and can be easily distinguished from the latter by the dark reddish as opposed to grayish color of the upperparts and by the shorter hind foot (less instead of more than 32.5 mm.).

=Sigmodon hispidus mascotensis= Allen

Hispid Cotton Rat; Spanish, Rata AlG.o.donera Setosa

_Sigmodon mascotensis_ Allen, Bull. Amer. Mus. Nat. Hist., 9:54, March 15, 1897, type from San Sebastian, near Mascota, Jalisco.

_Sigmodon hispidus mascotensis_, Bailey, Proc. Biol. Soc.

Washington, 15:108, June 2, 1902.

_Range._--Larger part of state.

_Specimens examined_, 4: nos. 100629, 3 mi. N Patzcuaro, 6,700 ft.; 100630, 2 mi. W Patzcuaro, 7,700 ft.; 100632, 1-3/4 mi. S Tacambaro, 5,700 ft.; 100631, 6 mi. S and 1 mi. E Tacambaro, 4,000 ft.

_Remarks._--Bailey (1902:109) records a "very large" specimen from Querendaro. Our specimens have shorter molariform tooth-rows than do those from nearer the type locality, for example, those from Tuxpan, Las Canoas, and Artenkiki, all three places in Jalisco.

=Sigmodon hispidus atratus= Hall

Hispid Cotton Rat; Spanish, Rata AlG.o.donera Setosa

_Sigmodon hispidus atratus_ Hall, Proc. Biol. Soc. Washington, 62:149, August 23, 1949, type from 6-1/2 mi. W Zamora, 5,950 ft., Michoacan.

_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

Volcano Mouse; Spanish, Raton de Los Volcanes

_Neotomodon alstoni_ Merriam, Proc. Biol. Soc. Washington, 12:128, April 30, 1898, type from Nahuatzin, 8,500 ft., Michoacan.

_Range._--Higher mountains of state.

_Specimens examined_, 22: nos. 52179-52184, 52186, 52193-52196, 52199, 52200, 52204-52212, all from Mount Tancitaro, distributed by localities as follows: 7,800 ft., 5; 7,850 ft., 3; 10,000 ft., 4; 10,200 ft., 5; 10,500 ft., 1; 10,800 ft., 1; 11,000 ft., 2; 11,400 ft., 1.

_Remarks._--The taking of specimens on Mount Tancitaro extends the known geographic range of _Neotomodon_ approximately 75 kilometers to the southwestward; the westernmost locality previously known was Nahuatzin, the type locality.

=Nelsonia goldmani= Merriam

Dwarf Wood Rat; Spanish, Rata Montera Minuscula

_Nelsonia goldmani_ Merriam, Proc. Biol. Soc. Washington, 16:80, May 29, 1903, type from Mount Tancitaro, Michoacan.

_Range._--Known only from the type locality.

_Remarks._--In the original description three specimens are recorded from the type locality.

=Neotoma latifrons= Merriam

White-throated Wood Rat; Spanish, Rata Montera Frentuda

_Neotoma latifrons_ Merriam, Proc. Biol. Soc. Washington, 9:121, July 2, 1894, type from Querendaro, Michoacan.

_Range._--Known only from the type locality.

=Neotoma ferruginea tenuicauda= Merriam

Ferruginous Wood Rat; Spanish, Rata Ferruginosa

_Neotoma tenuicauda_ Merriam, Proc. Biol. Soc. Washington, 7:169, September 29, 1892, type from north slope of Sierra Nevada de Colima, 12,000 ft., Colima.

_Neotoma ferruginea tenuicauda_, Howell, N. Amer. Fauna, 31:73, October 19, 1910.

_Range._--Probably all but southern tropical part of state.

_Specimens examined_, 4: nos. 100633 from 9 mi. SE Patzcuaro, 8,000 ft., and 52177, 51390, 51391, from Tancitaro, the elevation being given as 7,850 ft. on no. 52177.

_Remarks._--Our one specimen from 9 miles southeast of Patzcuaro was caught in a small steel trap set at a meat bait.

=Microtus mexica.n.u.s salvus= Hall

Mexican Meadow Mouse; Spanish, Metorito

_Microtus mexica.n.u.s salvus_ Hall, Univ. Kansas Publ., Mus.

Nat. Hist., 1:426, December 24, 1948, type from Mount Tancitaro, 11,400 ft., Michoacan.

_Range._--Known only from Mount Tancitaro at elevations of 7,800 to 11,400 feet.

_Specimens examined_, 14: nos. 51412, 51413, 52093, 52095-52099, 52101, 52103-52107, all from Mount Tancitaro, distributed by elevations as follows: 11,400 ft., 8; 11,000 ft., 2; 7,800 ft., 1; no elevation recorded, 3.

=Microtus mexica.n.u.s fundatus= Hall