Capable of being extended or expanded
- Acrodont; tongue broad and thick, not protractile; no osteoderms. Old World.
- Pleurodont; tongue broad and thick, not protractile; no osteoderms. America, Madagascar and Fiji Islands.
- Pleurodont; tongue short, villose, scarcely protractile, feebly nicked at the tip. With osteoderms at least upon the skull, where they roof in the temporal region.