Labial scale

The labial scales are the scales of snakes and other scaled reptiles that border the mouth opening. These do not include the median scales on the upper and lower jaws (rostral and mental scales). The term "labial" originates from "Labium" (Latin for "lip"), which refers to any lip-like structure. In snakes, there are two different types of labial scales: supralabials and sublabials. The numbers of these scales present, and sometimes the shapes and sizes, are some of many characteristics used to differentiate species from one another.
There are two different types of labial scales: