In preparing a list of kinds of mammals of which specimens havebeen saved from the Méxican state of Michoacán, two heretoforeunrecognized subspecies of the Méxican meadow mouse, Microtusmexicanus, have been found. Names for these and descriptions aregiven below.
Microtus mexicanus fundatus new subspecies
Type.—Male, adult, skin and skull; No. 100637, Univ. California Mus. Vert.Zool.; 3½ mi. S Pátzcuaro, 7,900 ft., Michoacán, México; March 9, 1943; obtainedby E. R. Hall, original no. 5882.
Range.—Known only from the vicinity of the type locality.
Diagnosis.—Size large (see measurements); color brown overlain with cinnamon;nasals expanded distally with premaxillary borders concave laterally;posterior border of orbit inclined posterolaterally; preorbital region andinterparietal region depressed; incisive foramina narrow; zygomatic archesparallel; tympanic bullae much inflated.
Comparisons.—Among named subspecies of Microtus mexicanus, M. m.fundatus most closely resembles M. m. mexicanus but differs as follows: Largerin all parts measured; pelage with slightly less buffy color and with the buffycolor that is present of a slightly lighter tint; posterior two-thirds of premaxillaryborder of each nasal concave rather than straight; posterior border oforbit forming more acute angle with sagittal plane of posterior part of skull;superior outline of nasals straight rather than depressed in posterior part;tympanic bullae more inflated both in vertical and horizontal planes.
From M. c. salvus, the subspecies next to the westward, fundatus differs asfollows: Averaging larger in all parts measured; less reddish on upper parts;underparts with more reddish color but the reddish of lighter tint; perinealregion buffy instead of plumbeous; nasals with premaxillary borders laterallyconcave rather than straight; superior outline of skull with nasal segmentsloping anteroventrally and interparietal segment sloping posteroventrallyrather than straight; posterior margin of orbit inclined posterolaterally thusforming an acute angle, instead of a right angle, with sagittal plane of braincase;zygomatic arches parallel rather than bowed outward; incisive foraminanarrower; tympanic bullae more inflated in vertical plane.
Relying on Bailey's (N. Amer. Fauna, 17:55, 1900) description of Microtusfulviventer, fundatus differs in much larger tympanic bullae.
Remarks.—The series of 59 specimens includes individuals ofseveral ages of both sexes. This has been a great advantage in makingcomparisons with individuals of geographically adjoining subspeciessince indivi