From the data given by Force (1935), Taylor (1936), and Kirn _et al._
(1949), and from our own data, we conclude that a typical specimen of
_gracilis_, meaning a specimen having the usual characteristics of the
species, has the following characteristics in combination: supralabials
6-6; infralabials 6-6; preoculars 1-1; postoculars 1-1; temporals 1 + 1
on each side; nasal divided below naris; supralabials 3 + 4 entering
orbit; mental in contact with chin-shields; all five dorsal scale counts
15; and plate divided. (In the present work we use the words usual,
unusual, typical, and atypical with neither quotation marks nor
apology).
Of the 244 specimens on which we could examine each of these
characteristics, only 125 (51.2%) have all of the typical
characteristics in combination. The 119 specimens that do not possess
all of the typical characteristics in combination include 31 (12.7% of
the 244) that lack at least two of the typical characteristics.