Parthenogenetic Cnemidophorus dixoni, consisting of color pattern classes A and B, is limited to a small area in the Chinati Mountains in southwestern Presidio Co., Texas, and a disjunct area in Hidalgo Co., New Mexico. In Presidio County lizards emerged from winter inactivity in April. Thereafter, adult lizards remained active into late August or early September; postneonates remained active until late October. Activity in C. dixoni A and/or B was observed on one or more occasions during every 15-min interval between 1020 h and 1930 h CDT during a 46-day field study between June 1989 and June 1990. No differences in mean cloacal body temperature were observed between juvenile and adult C. dixoni A or B, or among monthly samples. Mean cloacal body temperature for all individuals was 39.89 C +/- 0.15 (n = 113). Neonatal Cnemidophorus dixoni A and B hatched in July and August; they grew rapidly, became inactive for about 5 mo (November-March) and matured early in their 2nd summer at 67-73 mm snout-vent length. The life expectancy of C. dixoni appeared to involve parts of three activity cycles, or about 2 calendar yr. Clutch size varied from 1-5 with a mean of 2.90 +/- 0.08 for 94 clutches; snout-vent lengths of preserved gravid females varied from 67-97 mm with a mean of 82.12 +/- 0.57. Larger females had significantly larger clutches than smaller females; the model for the relationship is egg count = 0.09SVL - 4.51.
