The dorsal scales of cottonmouths are strongly keeled except that those of the two lower scale-rows on each side are weakly keeled. Also they are slightly larger than the others. Two apical pits are present on each dorsal scale. The shape of the scales and number of scale rows vary depending upon the position on the body. Scales on the neck are considerably smaller than those elsewhere on the body and are arranged in two or three more rows than those at mid-body. The skin in the region of the throat, neck, and fore-body is especially elastic and allows the swallowing of large prey. Posteriorly from the mid-body the scales decrease in size and become more angular, those on the tail tending to be rhomboidal and wider than long. In the region of the anus the number of scale rows diminishes rapidly, leaving only 12 to 14 rows at the base of the tail and only three rows immediately ahead of the tail tip. The tail ends in a spine composed of two scales: one scale covers the bottom, lower parts of the sides, and tip of the spine; and a shorter dorsal scale covers the top and upper parts of the sides of the basal two-thirds of the spine. The spine of embryos and young cottonmouths is blunt, but is pointed in most adults. TABLE 3.--Variation in Numbers of Supralabials and Infralabials in a Brood of Seven Cottonmouths. =========================================== | Number of | Number of | Number of | | individuals | supralabials | infralabials | | 1 | 7 | 9 | | 1 | 7 | 9-10 | | 2 | 7-8 | 8-9 | | 1 | 7-8 | 9 | | 1 | 8 | 9-10 | | 1 | 8-9 | 10 | ------------------------------------------- TABLE 4.--Analysis of Number of Scale Rows at Three Parts of the Body in 81 Cottonmouths.