Boulenger[[180]] has accepted Cope's principles, and, mainly by combining the Asinea with the Proteroglypha as Colubridae, has produced a logically conceived system, by far the best hitherto proposed. It has been followed in the present work. Boulenger's phylogenetic system stands as follows:–
I. No ectopterygoid; pterygoid not extending to quadrate or to mandible; no supratemporal (squamosal); prefrontal forming a suture with nasal; coronoid present; vestiges of pelvis.
Maxillary vertical, loosely attached, toothed; mandible edentulous; a single pelvic bone. .......... Typhlopidae, p. [593].
Maxillary bordering mouth, forming a suture with premaxillary, prefrontal, and frontal, toothless; lower jaw toothed; pubis and ischium present, latter forming a symphysis. .......... Glauconiidae, p. [594].
II. Ectopterygoid present; both jaws toothed.
A. Coronoid present; prefrontal in contact with nasal.
1. Vestiges of hind-limbs; supratemporal (squamosal) present.
Squamosal large, suspending quadrate. .......... Boidae, p. [596].
Squamosal small, intercalated in the cranial wall. .......... Ilysiidae, p. [594].