ample margin for even the largest racers, though inadequately small to permit ingress of a few of the largest black rat snakes, bull snakes and timber rattlers occurring locally. Ordinarily the snakes trapped were processed in the field and released immediately. The method of marking was essentially that of Blanchard and Finster (1933:334). Two subcaudals, one on the right side and one on the left, were clipped on each snake, and when these marks healed they left permanent scars. In the racer, as in most other colubrines, the subcaudals are divided into a double series, one on the left and one on the right. Scales of the left and right sides are placed alternately. At the base of the tail one or more undersized scales usually are present on each side, and there might be some question as to precisely where the count should begin. The rule followed was to exclude from the count any small basal scales on either side that did not extend medially to contact at least one scale of the opposite side. The scale designated as "one left" (or "one right") was the first to contact one of the opposite series, regardless of whether the former was of normal size or (as was usually the case) smaller and narrower than those following it. In marking, this "number one" scale was never clipped but was left as a point of reference since a base mark was needed from which to begin the count. The marks were read from left to right, for example U 5_l_ 2_r_, the "U" referring to the subcaudals or "urosteges," the "5_l_" indicating the fifth on the left side, and "2_r_" indicating the second on the right. The subcaudals clipped were the first 19 following the basal scale. When the 361 possible combinations all had been used, ending with U 20_l_ 20_r_, a new series was begun duplicating the first except that on each snake the first ventral (or "gastrostege") anterior to the anal plate was clipped on the left side (G1L) to distinguish these snakes from the series previously marked. Later, a third series, "G2R" was marked, and eventually a fourth series, "G3L" was started. There were many borderline instances in which the basal scale barely contacted one of the opposite side. In such instances the formula was written U 5_l__{ISB} 2_r_, the subscript ISB signifying "including small basal." In other instances a basal subcaudal barely failed to contact a scale of the opposite side and this condition was indicated by the subscript NSB--"not including small basal." The condition might be so nearly equivocal that on successive occasions the same formula might be read U 5_l__{ISB} 2_r_ and U 4_l__{NSB} 2_r_. Occasional misidentifications of individuals that resulted from such discrepancies were in most instances readily detected when the field records were transferred to individual file cards where the sex, size, and location of the snake at its previous captures were shown.