Scale Reduction in Snakes

Abstract

AMONG the first herpetologists to study reduction in dorsal scale rows in snakes, associated with the tapering body, was Ruthven (1908), who demonstrated that scale row reduction patterns were uniform in various groups of snakes and that different types of reduction characterize different groups. He examined the garter snake genus Thamnophis. Since then Blanchard (1921), Ortenburger (1928), and Stull (1940) have studied this matter in Lampropeltis, Coluber, and Pituophis, respectively. Blanchard and Stull pointed out that female snakes tend to have a larger number of scale rows than males, a difference which did not appear in Thamnophis. Ruthven and Stull relate the reduction in number of scale rows only with the tapering of the body. Another aspect of the problem was studied by Thompson (1914) and Procter (1919), who attempted to relate the reductions to internal anatomy. Mell (1929) correlated the number of scale rows with the type of food. The object of the present study is to formulate these scale reductions more exactly and to examine a wider range of genera in the hope of detecting other regularities in the mode of reduction and other correlations with taxonomic groups. To this end we have examined 345 specimens for scale reductions. The problem was suggested to us by Mr. Karl P. Schmidt and Mr. Clifford H. Pope, who have aided us throughout our study. They have been most helpful in the final preparation of the present paper.