Smith (1942a:360) diagnosed _Sceloporus melanorhinus calligaster_ as having fewer femoral pores than the other subspecies of _S. melanorhinus_ and as having the lateral belly patches in the males confluent in the midline. Examination of forty specimens from the Tepalcatepec Valley and the coastal regions of Michoacán does not substantiate this diagnosis. The number of femoral pores varies from 15 to 22 (18.9); 14 individuals (35%) had 20 or more femoral pores. Smith (_loc. cit._) stated that _S. melanorhinus_ in Oaxaca had 18 to 27 (21.6) femoral pores and that 77 per cent of the specimens had more than 20 femoral pores. Of the 24 males examined from Michoacán, 18 have the lateral belly patches separated in the midline. Usually they are separated by no more than one scale, but in some individuals they are separated by two or more scales. Although the above data minimize certain differences between the northern and southern populations of this species, certain of the color pattern characters seem to be diagnostic of the subspecies inhabiting the Pacific lowlands from Guerrero to Nayarit. Large adults of _S. m. calligaster_ have only a faint dorsal pattern, which in the subspecies _melanorhinus_ and _stuarti_ consists of a series of large, dark, interconnected triangles on the back. This pattern is present in young and small adults of _S. m. calligaster_; furthermore, in this subspecies the ventral coloration of the males differs from that found in the more southern populations. Adult males of _S. m. calligaster_ have a black throat, that changes to brilliant blue posteriorly, and a large white spot medially on the chin. This spot is present in some specimens from Oaxaca and Chiapas, but, if present, it is much smaller and less distinct than in specimens from Michoacán. In _S. m. calligaster_ the chest and midventral area are orange to salmon-color. A male from Lombardia in life was colored as follows: Dorsum grayish tan bearing faint bluish gray flecks; chest deep salmon-orange, this color continuing down midventral area to the somewhat paler groin; belly patches pale blue fading to pale green laterally; throat black anteriorly enclosing a white spot; throat blue posteriorly and bluish green posterolaterally. Individual lizards were observed to change in dorsal color from a pale ashy gray to a rather dull brown. Normally, inactive individuals and those observed on overcast days were dull brown. _Sceloporus melanorhinus calligaster_ is found in trees in riparian situations in the lowlands to elevations of about 1500 meters. It does not inhabit the arid tropical scrub forest in the Tepalcatepec Valley or on the coast, but in those areas is found in the gallery forests along streams and rivers. The lizards are wary and live high in the trees; they are especially difficult to locate in the rainy season, when the trees are in full leaf. ~Sceloporus pyrocephalus~ Cope