ABSTRACT The name Enicognathus melanauchen Jan belongs to a currently unrecognized but apparently valid species of small snake described some 140 years ago from an unknown locality in Bahia, Brazil; the unique specimen is in the Nationaal Natuurhistorisch Museum, Leiden. Attempts were unsuccessful to associate it with named genera of the colubrid subfamilies Xenodontinae, Dipsadinae, Colubrinae, and Natricinae; consequently, no basis was found for challenging the provenance. The genus Amnesteophis and tribe Amnesteophiini therefore are erected for the species. (The snake generic name Enicognathus and the emendation Henicognathus are both junior homonyms of bird names.) Assignment to Xenodontinae is partly on geographic grounds as well as on hemipenial and osteological comparisons with the other colubrid subfamilies mentioned. Tribe Amnesteophiini differs from other tribes in Xenodontinae by combination of three unusual character states: (1) straight-line configuration of posterior maxillary teeth; (2) lac...