2. Maxillary teeth equal, or increasing in size posteriorly.
a. Mandibular teeth 17 to 30; maxillary teeth 15 to 22.
Posterior maxillary teeth longest; mandibular teeth subequal, more than 20
Tropidonotus.
Posterior maxillary teeth longest; mandibular teeth not more than 20, posterior smallest
Zamenis.
Maxillary teeth subequal; mandibular teeth 20 to 25, posterior smallest
Coluber.
b. Mandibular teeth 14 or 15, subequal; maxillary teeth 12 to 15.
Maxillary teeth increasing in size