The type and two other specimens of Ephalophis greyi are described. The venom gland musculature is of the Demansia type, with an isolated muscle running from the quadrate to the rear of the venom gland. The only other hydrophiine with the Demansia pattern of venom gland musculature, Hydrophis mertoni Roux, is referred, for this and other reasons, to the genus Ephalophis as E. mertoni (Roux). Some notes on a skull of E. mertoni are presented, along with a revised diagnosis of Ephalophis. The Demansia pattern of venom gland muscles seen in Ephalophis is primitive for the Hydrophiinae and other members of that subfamily have secondarily taken on a Glyphodon type of musculature of the venom gland by loss of the muscle slip from quadrate to gland. The Demansia group of terrestrial elapids, particularly the genus Drepanodontis Worrell, stand close to the origin of the Hydrophiinae. A classification of the Hydrophiinae into three generic groups is presented, with Ephalophis, Aipysurus, and Emydocephalus referred to an Aipysurus group.