Produced by Chris Curnow, Tom Cosmas, Joseph Cooper and the Online Distributed Proofreading Team at http://www.pgdp.net ~University of Kansas Publications~ ~Museum of Natural History~ Vol. 10, No. 9, pp. 587-598, 2 figs. May 2, 1960 A New Subspecies of Lizard, Cnemidophorus sacki, from Michoacán, México BY WILLIAM E. DUELLMAN ~University of Kansas~ ~Lawrence~ 1960 ~University of Kansas Publications, Museum of Natural History~ Editors: E. Raymond Hall, Chairman, Henry S. Fitch, Robert W. Wilson Volume 10, No. 9, pp. 587-598, 2 figs. Published May 2, 1960 ~University of Kansas~ Lawrence, Kansas PRINTED IN THE STATE PRINTING PLANT TOPEKA, KANSAS 1960 28-2494 A New Subspecies of Lizard, Cnemidophorus sacki, from Michoacán, México BY WILLIAM E. DUELLMAN The systematic status of the populations of lizards assignable to _Cnemidophorus sacki_ in western México (Sonora southward to Jalisco) has been reviewed in detail by Zweifel (1959, Bull. Amer. Mus. Nat. Hist, 117 (2):57-116), who stated that the use of the specific name _sacki_ for the western populations rests upon a reasonable, but as yet unproved, assumption that intergradation occurs. Although Zweifel examined specimens of the nominal subspecies from the upper Balsas Basin, he did not study specimens from the intervening area--the Tepalcatepec Valley in Michoacán. Field studies and the examination of large series of preserved specimens of _Cnemidophorus_ from the Tepalcatepec Valley show the presence of _Cnemidophorus sacki_ in the region between the ranges of _C. sacki sacki_ in the upper Balsas Basin and _C. sacki occidentalis_ in Jalisco and southern Nayarit. Furthermore, the populations of _sacki_ inhabiting the Tepalcatepec Valley have characters of scutellation and coloration that distinguish them from other described subspecies of _sacki_. In recognition of the important contributions to the systematics of the genus _Cnemidophorus_ made by Dr. Richard G. Zweifel, I propose that the subspecies of _Cnemidophorus sacki_ in the Tepalcatepec Valley be named as follows: +Cnemidophorus sacki zweifeli+ new subspecies