In a message dated 7/31/00 5:26:31 PM EST, archosaur@usa.net writes: << Of those 32 snake species known to possess sacs, all but one are colubrids (the wild card here is _Ophiophagus hannah_, the only cobra known to have them) and the majority appear to be arboreal. >> Most interesting. Air sacs and arboreal. Makes one pause...