Snake lizards, also known as earth dragons and lizard snakes, are a collective name for the subfamily of lizards in the family Lizards. It is a primitive lizard without limbs, resembling a snake, but not a snake. The significant difference in appearance from the snake is the abdominal scales, not the broad and short scales that snakes only have, but multiple rows of scales similar to the dorsal scales. The surface of the body is covered with square or diamond-shaped scales, arranged in rows vertically and horizontally. The distribution is mostly concentrated in the bottom soil of the middle and low altitude forests between 1000 and 2000 meters above sea level.
The length of the body can reach about 18 cm, and the tail length can reach up to 1.8 times the length of the body. Adults are predominantly brown , dark or light , with many blue spots ; juveniles have dark or black longitudinal spots on both sides. All snake lizards are non-venomous. The main diet is the larvae of earthworms, slugs or beetles. Like all lizard species, the tail breaks itself. Snake lizards are scarce and secretive in nature, and are not easy to see. It prefers to inhabit deciduous piles or soils at the bottom of moist natural forests.
The main differences between snake lizards and snakes are: (1) Snake lizards have closed eyelids; snakes do not. (2) More than two-thirds of the length of the snake lizard is the tail; the tail of the snake is shorter than the body. (3) Snake lizards have holes in the outer ear; snakes do not. (4) The body of the snake lizard is covered with hard square scales, arranged in a ring, and the abdominal scales are small and multi-columned; the abdominal scales of the snake are large and single, with residual traces of hind limbs on both sides of the cloaca. (5) The tail of the snake lizard is easy to break automatically; the snake will not break the tail on its own.
The snake lizard family can be divided into 4 different subfamilies, two of which have members with sound limbs and the other two have no limbs and resemble snakes or earthworms. The two limb-sounding subfamily are: the subfamily Lateral fold lizard and the subfamily Lizard, both of which are limited to the New World. The subfamily Lateral folded lizards are arboreal or land-dwelling in the southwestern Canada to the tropical regions of Central America, with arboreal members with tails that can be wound. The subfamily Lizardidae is mainly distributed in the Caribbean islands, resembling a stone dragon with small limbs.
The two subfamilies without limbs are: the subfamily Snake Lizard and the Subfamily Worm Lizard. The subfamily Snake Lizard is the most famous of all the footless lizards, widely distributed, in addition to North America, can also be seen in Eurasia and northern Africa, is the only representative of the family can be seen in the Old World; the appearance is very similar to the snake, but there are movable eyelids, there are ear holes; people usually refer to this subfamily. The body of the subfamily Worm Lizard is small, burrowing like earthworms, with movable eyelids but no ear piercings.