The spermatogenic cycle of _T. ornata_ as here reported, differs in no important respect from those of _Thamnophis_, _Sternotherus odoratus_, or _Terrapene carolina_, except that in _T. ornata_ the cycle begins and ends somewhat later in the season of activity. In most of the lizards that have been studied (Fox, 1952:492-3), spermatogenesis reaches a peak in spring (more or less coincident with the mating period and with ovulation) and the germinal epithelium remains active in winter. _Sternotherus_, _Terrapene_, and _Thamnophis_ are alike in completing spermatogenesis late in the season and storing spermatozoa, in the seminiferous tubules or in the epididymides, during hibernation. It is noteworthy that, in the turtles and snakes mentioned above, sperm produced in autumn are used to fertilize eggs laid in the following year, and mating [with the exception of _Thamnophis elegans_, (Fox, 1956)] occurs in both spring and autumn. It is not definitely known in any of these instances, whether sperm resulting from autumn or spring inseminations (or both) fertilize the eggs. Risley (1933:693) found motile sperm in the oviducts of female _Sternotherus odoratus_ that had recently emerged from hibernation; he believed that spring mating, although it commonly occurred, was not necessary to fertilize eggs. Disadvantages, if any, of completing spermatogenesis well in advance of ovulation seem to be at least partly counteracted by two annual mating periods or by mating throughout the season of activity. Sexual Cycle of Females The following account of oögenesis is based on examination of preserved ovaries from 68 mature specimens. The ages of most specimens were known, inasmuch as the specimens were used in studies of growth as well as gametogenesis. Other data were obtained from adult females that were dissected but not preserved, and from immature females. [Illustration: FIG. 4. Seasonal fluctuations in ovarian weight in _T. o. ornata_, as determined by examination of 60 specimens from eastern Kansas.] Size of ovarian follicles was determined by means of a clear plastic gauge containing notches 5, 10, 15, 20, and 25 millimeters wide. The number of follicles within a given size range could be quickly determined by finding the smallest notch into which the follicles fit. It was necessary to weigh all ovaries after preservation since some of them had not been weighed when fresh. Since all ovarian samples were preserved in the same manner, weights remained relatively the same. Preserved material was lighter than fresh by an average of 13 per cent. Follicles less than one millimeter in diameter were not counted. Corpora lutea and corpora albicantia were studied under a binocular dissecting microscope. No histological studies were made of the female reproductive system.