The Algerian three-toed skink (Chalcides mertensi ) is a species of "grass-swimming" skink with an elongated serpentine shape and reduced limbs. It is endemic to north-western Africa.
It is native to northern Algeria and northern Tunisia, where it occurs on the Mediterranean coast.
The Algerian three-toed skink lives in forested areas in northern Algeria, and in semi-arid maquis-type habitats in Algeria and Tunisia. It prefers humid, sunny areas with dense vegetation within grassland, meadows, areas close to streams, hedges, open cork oak forest, and the edges of cultivated areas. It is also known from tall herbaceous grassland. The females give birth to formed young. It has been recorded from sea level up to 1,500 m above sea level.
The Algerian three-toed skink is listed as least concern but is threatened by habitat loss caused by overgrazing and the conversion of land to agricultural and urbanisation. It occurs in the Djurdjura National Park in Algeria but is not known to occur in any protected areas in Tunisia.