Burton's legless lizard (Lialis burtonis) is a species of lizard in the family Pygopodidae. The species lacks forelegs and has only rudimentary hind legs. Pygopodid lizards are also referred to as "legless lizards", "flap-footed lizards" and "snake-lizards". This species is native to Australia and Papua New Guinea. Taxonomy English zoologist John Edward Gray described Burton's legless lizard in 1835. The specific name, burtonis, is in honour of British army surgeon Edward Burton (1790–1867). Burton's legless lizard (Lialis burtonis) is a member of the genus Lialis within the family Pygopodidae. There are approximately 40 species in the family Pygopodidae, however, Burton's legless lizard and another species (L. jicari) are the only species that fall within genus Lialis. Members in genus Lialis are considered analogous to macrostomatan snakes as these taxonomic groups have functionally similar adaptations such as the ability to swallow relatively large prey whole. However, their resemblance to snakes is merely superficial example of convergent evolution, and they are not closely related. Differences between legless lizards and snakes include the lack of venom glands in legless lizards, their inability to constrict prey, the presence of a fleshy tongue rather than a forked tongue, visible ear holes, and remnant hind limbs. Burton's legless lizard and the Pygopodidae, as a whole, are members of the infraorder Gekkota, meaning that they are essentially legless geckos. Pygopods are the namesake of the Australasian gecko superfamily Pygopodoidea (sometimes called Diplodactyloidea), and they are the sister taxon to legged geckos in the family Carphodactylidae. Description Burton's legless lizard has significant morphological adaptations to enable it to deal with large struggling prey items. The first adaptation is a skull with an elongated snout that may, along with its pointed, recurved and hinged teeth, be an adaptation that assists it to grip its prey. In addition, this elongated snout may also promote binocular vision which would allow strikes to be more accurately directed. Another adaptation that assists Burton's legless lizard to hold its prey is its flexible mesokinetic and hypokinetic joints which allow its jaws to encircle prey. Lastly, the ability of the species to retract its eyes is of key importance as it is a visual predator that relies on eyesight and this adaptation effectively protects them during conflict. Distribution and habitat Burton's legless lizard occurs almost Australia wide but it is absent in parts of southern Australia including Tasmania. This species is also found in Papua