Among small mammals accumulated, from Wyoming, in the Museumof Natural History of the University of Kansas, specimens ofthe wide-spread species Thomomys talpoides are abundantly represented.Subspecific names are available for most of these, butspecimens from the Sierra Madre Mountain Range of Wyoming andColorado prove upon comparison to pertain to an heretofore unnamedsubspecies which may be described and named as follows:
Thomomys talpoides meritus new subspecies
Type.—Male, adult, skull and skin, no. 25628 Mus. Nat. Hist. Univ. Kansas;from 8 mi. N and 19-½ mi. E Savery, 8800 ft., Carbon County, Wyoming; obtainedon July 19, 1948, by George M. Newton; original no. 4.
Range.—Sierra Madre Mountain Range of southern Wyoming and northernColorado.
Diagnosis.—Size small (see measurements); color dark, upperparts in wornpelage of July darker than (near, n) Raw Umber (capitalized terms are ofRidgway, Color Standards and Color Nomenclature, Washington, D. C., 1912)and in fresh pelage of August between (near, 16') Prout's Brown and MummyBrown; skull small; relative to basilar length, skull narrow across rostrum,zygomata and mastoids; nasals short and posteriorly truncate; premaxillae extendingbehind nasals; temporal lines faint and divergent posteriorly.
Comparisons.—From Thomomys talpoides rostralis (North Platte River Valley,SW of Saratoga, Wyoming), the subspecies to the east and south, T. t.meritus differs in: Lesser size, darker color, smaller and slenderer skull. Theslenderness is especially noticeable in the breadth across the zygomata, mastoids,and rostrum. From Thomomys talpoides clusius (topotypes), the subspeciesto the north and west, T. t. meritus differs in: Color much darker; rostrumlonger; skull narrower across mastoids and zygomata; tympanic, and alsomastoid, bullae smaller. Resemblance to T. t. clusius is shown in the narrownessof the skull interorbitally and in the shortness of the tooth-row.
Remarks.—The specimens of Thomomys from Wyoming on whichthe name T. t. meritus is based were obtained by Mr. E. LendellCockrum and his associates with the thought that intergradationmight be shown between T. t. rostralis to the east and T. t. clusius tothe west. The animals showed instead, that there was a subspeciesdiffering from each of the two mentioned subspecies in small size,dark color and slenderness of skull. Acknowledgment of assistance[Pg 222]with field work is made to the Kansas University Endowment Association.