text: II. Quadrate suspended from the supratemporal; mandible at least as long as the skull; pterygoids extending to quadrate or mandible.
  A. Mandible with coronoid bone; nasals in sutural contact with frontals and prefrontals; transverse bone short, not projecting much beyond cranium; maxillary not half as long as mandible, which is not longer than skull (to occiput): Eryx.
  B. No coronoid bone; nasals isolated.
  1. Maxillary elongate, not movable vertically.
  a. Maxillary half as long as mandible.
  Supratemporal half as long as skull, projecting far beyond cranium; mandible much longer than skull: Tropidonotus.
  Supratemporal not half as long as skull, projecting far beyond cranium; mandible much longer than skull: Zamenis.
  Supratemporal not half as long as skull, projecting but slightly beyond cranium; mandible much longer than skull: Coluber.
  Supratemporal not half as long as skull, not projecting beyond cranium; mandible not longer than skull: Coronella, Contia.
  b. Maxillary not half as long as mandible, which is longer than skull; supratemporal not half as long as skull, projecting beyond cranium.
  Quadrate longer than supratemporal; maxillary much longer than quadrate, nearly straight in front of prefrontal; a large vacuity between the frontal bones and the basisphenoid: Coelopeltis.
  Quadrate not longer than supratemporal; maxillary little longer than quadrate, strongly curved in front of prefrontal:Macroprotodon