In 88 racers caught in the summer of 1962 the following measurements were recorded: Head length, from tip of snout to angle of jaw; maximum head width; greatest diameter of eye; circumference of neck; circumference at mid-body; circumference at posterior end of body; and circumference of tail-base. Because the measurements were small, and were made in the field on active, struggling snakes, a high degree of precision could not be attained, and the range of error was several per cent, with occasional relatively large errors. Nevertheless, ontogenetic trends are clearly indicated. Most of the racers measured were adults of small to medium size--in the range 500 to 799 millimeters, snout-vent length. Twelve females and seven males ranged from 800 to 1035 millimeters, and seven young (all females) were less than 500 millimeters. In measurements other than circumference of tail-base, significant differences could not be found between males and females of the same size group; therefore the sexes were combined to obtain larger series. Table 3. Bodily Proportions (Expressed as Ratio of Snout-vent Length) in Racers of Different Sizes ==========================+===============+===============+============== | Large | Medium | Small Size Group |(more than 800 | (500 to 800 |(less than 500 | millimeters) | millimeters) | millimeters) --------------------------+---------------+---------------+-------------- Length of head | 3.61 ± .036 | 3.82 ± .025 | 5.39 Width of head | 1.93 ± .049 | 2.02 ± .023 | 2.53 Diameter of eye | .56 ± .008 | .63 ± .009 | 1.00 Circumference of neck | 4.71 ± .082 | 5.05 ± .052 | 6.64 Circumference at mid-body | 7.11 ± .238 | 7.66 ± .082 | 8.58 Circumference at posterior| | | end of body | 5.06 ± .113 | 5.03 ± .061 | 5.90 Circumference of tail | 4.23 ± .113[1]| 4.22 ± .075[1]| 4.66[1] at base | 4.47 ± .171[2]| 4.66 ± .043[2]| --------------------------+---------------+---------------+-------------- [1] Females. [2] Males. Table 3 shows that as compared with adults, the small young racers have stouter, stubbier bodies, relatively large heads, and, especially, large eyes. Allometric growth seems to continue throughout life and the changed proportions of the adults are accentuated in the largest and oldest individuals. _Lepidosis_