Apical pits are translucent epidermal spots located on the posterior end (the apex) of the dorsal scales of some snake species (Gloyd and Conant, 1990). In the majority of species with these structures, the dermis in the region of an apical pit is densely pigmented with melanin, while the corresponding region ofthe epidermis is not pigmented. This difference in pigmentation between the dermis and epidermis causes the apical pits to appear pigmented in the actual animal, but not pigmented in the shed stratum corneum (Figure 1). These structures may be single (e.g., Carphophis spp., Diadophis spp.) or paired (e.g., Nerodia spp., Regina spp.). The location of the dorsal scale pits varies among genera. For example, they occur within the apical lobe (see Figure 2) in Lampropeltis and Pantherophis; they are found at the base of the lobe in Nerodia and Regina; they are found well beyond the lobe in some species of Agkistrodon. Apical pits usually are found on dorsal scales of the nape, midbody and tail. However, these structures may be restricted to certain regions of the body, such as the nape in Storeria (Gray, 2002), or just the nape and tail as in some species of Thamnophis. Some genera appear to lack apical pits (e.g., Farancia and Virginia).