The Infraorder Alethinophidia is divided into 6 superfamilies: 1) Anilioidea (with palatine meeting palatal plate of vomer to form a complete bony floor to choanal passage; very large footplate of stapes facing laterally in a juxtastapedial fossa); 2) Booidea (with a wing of the prefrontal roofing the aditus conchae, shaft of stapes extending to middle or lower part of quadrate; left lung large and no tracheal lung); 3) Acrochordoidea (with juxtastapedial fossa barely indicated; frontal-parietal contact slightly kinetic; greatly reduced prefrontal bone); 4) Tropidophoidea (with tracheal lung and with left lung vestigial or absent; stapes meeting upper end of quadrate; no protractor quadrati muscle); 5) Bolyerioidea (with maxillary bone divided by an articulation, the skull otherwise much as in Tropidophoidea; left lung small and no tracheal lung); 6) Colubroidea (so far as known [but many forms uninvestigated], with a protractor quadrati muscle; primitively with serous [venom-producing] gland cells in upper lip; except in some viperids, with only one carotid artery). The Anilioidea are divided into 4 families: Loxocemidae, Xenopeltidae, Aniliidae, and Uropeltidae. The Uropeltidae, characterised by lack of premaxillary teeth and by unforked sulcus spermaticus, are divided into two subfamilies, Cylindrophinae (with pelvic girdle) and Uropeltinae (without pelvic vestiges); the Cylindrophinae are represented in the area covered by Cylindrophis aruensis Boulenger of the Aru Islands, closely related to C. boulengeri Roux of Wetar and the Babber Islands. A key to Lesser Sunda, Moluccan, and Aru Island species of Cylindrophis is presented.
The Booidea contains a single family Boidae, divided into two subfamilies: Pythoninae (with supraorbital bone; palatine not adapted to motion independent of maxilla) and Boinae (no supraorbital; palatine adapted to erection independent of maxilla). The New Guinea members of the Pythoninae are divided into three genera: Liasis Gray (tail not prehensile, most scales with apical pits), Python (tail prehensile, no scale pits or only a few scattered scales with pits), and Chondropython (similar to Python but hemipenis unforked, coronoid bone reduced, and back ridged). Chondropython is monotypic, for C. viridis (Schlegel). Liasis is represented in New Guinea and the Bismarck Archipelago by: L. mackloti Dumeril and Bibron (including L. fuscus Peters as a synonym); L. papuanus Peters and Doria (specifically distinct from the Australian L. olivaceus Gray); L. albertisii Peters and Doria (specifically distinct from L. mackloti or "fuscus" and here first recorded from Mussau Island); L. boa (Schlegel) (previously referred to a monotypic genus Bothrochilus; erroneous records from New Guinea are discussed). Python is represented by: P. amethistinus (Schneider) (here removed from Liasis and considered closely related to the Asiatic P. reticulatus); P. boeleni (Brongersma) (previously referred to Liasis); P. spilotus (Lacepede) (previously referred to Morelia Gray, but linked to P. amethistinus by P. boeleni). All species show some geographic variation and distribution is discussed; records of pythons from the Solomon Islands are probably erroneous.