_Range._--Semitropical and tropical western part of the state. _Specimens examined_, 14: nos. 52018-52023, 52063-52070, from 1,040 ft., 10 kms., W Apatzingan. _Remarks._--These specimens are notably paler and have shorter tooth-rows than those referred to _O. c. regillus_. =Oryzomys fulvescens lenis= Goldman Fulvous Rice Rat; Spanish, Rata Arrocera Pigmea _Oryzomys fulvescens lenis_ Goldman, Proc. Biol. Soc. Washington, 28:130, June 29, 1915, type from Los Reyes, Michoacán; N. Amer. Fauna, 43:91, September 23, 1918. _Range._--Semitropical parts of state. _Remarks._--The type and one topotype so far as we know are the only specimens of this species to have been obtained from the state. The size is hardly larger than that of a large _Reithrodontomys_. =Sigmodon melanotis= Bailey Fulvous Cotton Rat; Spanish, Rata Algodonera Leonada _Sigmodon melanotis_ Bailey, Proc. Biol. Soc. Washington, 15:114, June 2, 1902, type from Pátzcuaro, 7,000 ft., Michoacán. _Range._--Central Michoacán, as now known. _Specimens examined_, 8: nos. 100623-100626, 52089-52092, distributed by localities as follows: 2 mi. W Pátzcuaro (7,400 and 7,700 ft.), 2; 3-1/2 mi. S Pátzcuaro, 7,800 ft., 2; Tancítaro, 6,000 ft., 4. _Remarks._--This species was taken along with the species _S. hispidus_ two miles west of Pátzcuaro, 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 Algodonera Setosa _Sigmodon mascotensis_ Allen, Bull. Amer. Mus. Nat. Hist., 9:54, March 15, 1897, type from San Sebastián, 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 Pátzcuaro, 6,700 ft.; 100630, 2 mi. W Pátzcuaro, 7,700 ft.; 100632, 1-3/4 mi. S Tacámbaro, 5,700 ft.; 100631, 6 mi. S and 1 mi. E Tacámbaro, 4,000 ft. _Remarks._--Bailey (1902:109) records a "very large" specimen from Queréndaro. 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 Algodonera 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., Michoacán. _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.