In some instances racers recaptured after periods of years retained conspicuous scars where scales had been clipped, but in other instances the marks had become obscure, and in fact the only trace of a mark might be a slight narrowing or notching of part of the scale originally clipped. Snakes caught and marked early in life probably retained more power of regeneration than those clipped after the attainment of maturity, but otherwise the basis for difference in extent of regeneration was not evident. In the same snake, three scales, all clipped on the same day, might show much different degrees of regeneration after the lapse of a year or more. In general, obscuring of marks by regeneration was a source of inconvenience rather than of error; only a negligible percentage of the recaptured racers had marks so obscure that their identities might have been seriously questioned, and it is doubtful that any marks were lost completely by regeneration. Racers found in traps were removed, measured (snout-to-vent length, tail length), weighed in a cloth bag suspended from spring scales, and marked. The mouth was forced open and the snake was examined for flukes. Enamel paint of a bright color, red, green, yellow, blue or orange was smeared on the snake to gain information regarding the time of molt. The stomach was palpated for recently ingested food items, and any detected were forced up into the gullet to be identified, then were squeezed back into the stomach. The rear part of the body was palpated to detect undigested material in the gut, and if any was present, an attempt was made to squeeze out the fecal material, using only light pressure, with care not to injure the racer. The inside of the trap and the ground beneath it were inspected for fecal material that might have been voided while the snake was confined. Any scatological material obtained was wrapped in a paper towel, labelled and brought back to the laboratory where it was stored. Eventually each scat was soaked for a day or more in a detergent solution, rinsed in running water in a fine gauze bag, dried, and placed with its label in a cellophane envelope for subsequent microscopical study. Various items concerning reproductive condition were also routinely recorded. In females the ventral surface was palpated at the rear end of the body to detect the genital bursa or vagina, which in sexually mature individuals has a much thickened wall, and can be felt as a distinct lump. Males were likewise tested for sexual maturity by pipetting a small amount of fluid from the cloaca into a vial and returning it to the laboratory where it was examined microscopically for motile sperm. Also, sperm samples were often taken from males at different times throughout the season of activity, and cloacal samples from females occasionally were checked for sperm as evidence of recent copulation.