SYNOPSIS. The discovery of parthenogenesis in reptiles came about through the casual observation ol the lack of males in several species of lizards. Nineteen all female species and subspecies from five genera and three families of lizards have been named or recognized. Actual proof of parthenogenesis, however, has been demonstrated foi only seven ol these. Studies in variation of parthcnogens versus the variation ot sympatric bisexual species have been made on six species. Tn general the paithenogens arc much less variable than bisexual species. Males have been found in most ot the paithenogens studied. At least some of these seem lo result from crosses between paithenogens and males of sympatric bisexual species. In a few instances, however, this seems unlikely. The evidence supporting the In brid origin of these males rests on a few studies which show that these males have one more genome than the female paitheuogens they resemble. The evolution and origin of paithenogens probably is through hybridization followed by fuither hvbridization in some genera leading to triploidy. Evidence for these Inpotheses is piovided by a number of karyotypc studies, skin transplants, and studies of various proteins. One study indicates that the somatic chromosome number is icstored during oogenesis by an endoduplication immediately preceeding meiosis. Cuemuluphonis uniparens, the species in which this phenomenon was demonstrated, is a triploid Evolutionary aspects ol parthenogenesis are discussed.