Although Michoacán has not previously been included in the range of this lizard, it was first collected in the state by Gadow in 1908 (BMNH 1914.1.28.69 from Araparicuaro). The description of _S. heterolepis_ given by Smith (1939:197) can be supplemented by data on the 23 specimens now in the collections of the Museum of Zoology at the University of Michigan. All have two canthals; there are 55 to 71 (63.6) scales in the middorsal row; 1 to 3 rows middorsally are somewhat enlarged and bordered on either side by a row of larger scales bearing high keels. There are 14 to 20 (16.2) femoral pores. Eight adult males have snout-vent lengths from 49 to 61 (58.0) mm. and tail lengths from 57 to 74 (66.0) mm.; four adult females have snout-vent lengths from 52 to 57 (55.2) mm. and tail lengths from 60 to 66 (63.5) mm. The smallest of eight juveniles has a snout-vent length of 28 mm. and a tail length of 32 mm. The dorsum in adults is pale grayish brown; there are three irregular chevron-shaped dark marks and a triangular dark brown mark above the insertion of the hind limbs; on the tail are dark brown rings. There are scattered faint blue flecks on the flanks and narrow transverse dark lines on the lower limbs. Males have pale bluish green belly patches and an orange-salmon-colored throat; the belly in females is pale orange-tan. The juveniles have a more contrasting color pattern; the dark chevrons on the dorsum are bordered posteriorly by pale gray. In Michoacán this species has been obtained in pine and pine-fir forests from 1800 to 2700 meters. On Cerro Barolosa and at Dos Aguas, both in the Sierra de Coalcomán, the lizards were found beneath the bark of dead, standing pines. In the Sierra de Coalcomán _Sceloporus heterolepis_ seems to fill the niche of the small arboreal _Sceloporus_ in the coniferous forest in southwestern México, a position held by _S. grammicus microlepidotus_ in the Cordillera Volcánica; the latter species does not occur in the Sierra de Coalcomán. Five specimens of _Sceloporus heterolepis_ are known from the Cordillera Volcánica, whereas 603 of _S. grammicus microlepidotus_ have been collected there. The ecological relationships that exist between the two species in the Cordillera Volcánica are not known. Insofar as is known, _Sceloporus heterolepis_ reaches the southern limits of its range in the Sierra de Coalcomán and in the western part of the Cordillera Volcánica. Other records for the species are from the Sierra Madre Occidental in Jalisco. Langebartel (1959) described _Sceloporus shannonorum_ from the mountains near the Durango-Sinaloa border; the single specimen of _S. shannonorum_ differs significantly from _S. heterolepis_ only in having fewer dorsal scales (48). The acquisition of additional material, especially from Nayarit and northern Jalisco, probably will provide a basis for showing that these two populations are conspecific. ~Sceloporus horridus oligoporus~ Cope