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.
                        
                     
                                                         
                
                    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.
                                            
                            by William Edward Duellman
                            
                                7 Nov, 2018                            
                            
                         
                                        
                                                                        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 
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                                                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. Less