The common slow-worm (Anguis fragilis) is a species of legless lizard native to western Eurasia.

Common slow worms are semifossorial[2] (burrowing) lizards, spending much of their time hiding underneath objects.

Under the scales there are bony plates (osteoderms), so that slow worms crawl much more stiffly and clumsily than snakes.

The relatively small eyes have movable, closable eyelids (these are fused in snakes) and round pupils.

To lick, i.e. to absorb odorous substances, slow worms have to open their mouths slightly, as they lack the gap in the upper lip that snakes possess.

The gestation period of the females lasts 11 to 14 weeks, and subsequently, between mid-July and the end of August, and sometimes even later, they usually give birth to between eight and twelve young (extreme values: 2 to 28).

Slow worms are ovoviviparous; at birth, the 7 to 10 cm long young animals are in a very thin, transparent egg shell, which they pierce immediately afterwards.

Predators of A. fragilis include adders, badgers, birds of prey, crows, domestic cats, foxes, hedgehogs, pheasants and smooth snakes.

[22] In the United Kingdom, the slow worm has been granted protected status, alongside all other native British reptile species.

[26][27][28] Members of the genus Anguis, to which the slow worm belongs, first appeared in Europe during the Mammal Paleogene zone 14, between 43.5 and 41.2 million years ago, corresponding to the Lutetian stage of the Eocene.