A Proposed Method of Expressing Scale Reductions in Snakes

THE USE of scale reduction formulae, introduced by Ruthven (1908) and revised and expanded by Schmidt and Davis (1941) and Clark and Inger (1942), has aided greatly in the study of variation in snakes and has been used by numerous subsequent workers. Many workers, however, have made changes in the original form, and some of the changes are of such magnitude that the results are not strictly comparable. For this reason I believe that the time is right for proposing a standard system of notation which combines the advantages of the various forms and does away with most of their disadvantages. The significance of using detailed dorsal counts, with particular attention to the scale rows which are added and dropped, was first pointed out by Ruthven (1908: 16-21) in gartersnakes. Thompson (1914: 384) indicated, in the form of a table, the point of loss of dorsal rows by reference to the ventral count opposite the drop. Later, Blanchard (1921: 9-13) initiated an abbreviated form of notation