One hundred of the skinks marked as adults or subadults and recaptured after intervals of months, including, in most instances, one or more hibernation periods, represent in the aggregate, 87 years of growth. These records show that after minimum adult size of 65 mm. is attained, growth slows abruptly, and that by the time a length of approximately 75 mm. is attained in most instances growth has become extremely slow in males and has virtually stopped in females. Males attain a maximum size several millimeters larger than that of females. Individuals differ greatly in their growth, however; some adults continue to grow rapidly till they near the maximum size, whereas others apparently stop growing when they are still below average adult size. Unusually large specimens are not necessarily old, but may have attained their size only a year or two after reaching maturity through the accelerated growth resulting from abundant food and predisposing genetic factors. Likewise, unusually old individuals are not necessarily the largest, but may be only a little above average adult size. It may be assumed that no growth occurs during the period of winter dormancy, which occupies approximately half the year in the population studied. To compute growth rates, in those recaptured after an intervening hibernation, periods of hibernation, arbitrarily estimated as six months, were subtracted from the time elapsed between captures. Table 11. Average Growth Rate in a Selected Sample of Skinks of Adult Size. ============+====================+==================== | Males | Females |----------+---------+----------+--------- SIZE GROUP | Average | Number | Average | Number |growth mm.|of skinks|growth mm.|of skinks |per month |in sample|per month |in sample ------------+----------+---------+----------+--------- 65-68 mm. | 1.4 | 11 | .8 | 12 69-72 mm. | .7 | 12 | .4 | 21 73-76 mm. | .7 | 13 | .3 | 21 77-80 mm. | .4 | 7 | .... | .... ------------+----------+---------+----------+--------- Opportunity to compare the rapid growth of young during their first year of life with the relatively slow continued growth after attainment of sexual maturity is afforded by the records of skinks caught and marked while yet immature and recaptured in two or more successive years after their attainment of sexual maturity. The records of selected individuals of this group are presented below. With the exception of number three, all in this series are of the 1949 brood, and probably all hatched within a two-week period. Table 12.--Records of Individual Skinks Marked as Young and Recaptured Repeatedly After Attainment of Adult Size, Showing Trend of Progressively Slowing Growth.