2. No vestiges of limbs; squamosal absent. .......... Uropeltidae, p. [595].
B. Coronoid absent; squamosal present.
1. Maxillary horizontal; pterygoid reaching quadrate or mandible.
Prefrontal bone in contact with nasal. .......... Xenopeltidae, p. [605].
Prefrontal not in contact with nasal. .......... Colubridae, p. [606].
2. Maxillary horizontal; pterygoid not reaching quadrate or mandible. .......... Amblycephalidae, p. [637].
3. Maxillary vertically erectile, perpendicularly to ectopterygoid; pterygoid reaching quadrate or mandible. .......... Viperidae, p. [637].
For ordinary practical purposes this synopsis is useless, being based entirely upon anatomical characters, not all easily ascertained. The following characterisation of families may therefore be preferred:–
Eyes vestigial; no teeth in the lower jaw; without enlarged ventral scales. .......... Typhlopidae.
Eyes vestigial; teeth restricted to the lower jaw; without enlarged ventral scales. .......... Glauconiidae.