Lemur of mouse lemurs, the gray mouse lemur ("M. murinus"), golden-brown mouse lemur ("M. ravelobensis"), and Goodman's mouse lemur ("M. lehilahytsara") were considered the same species until recently, when genetic tests identified them as cryptic species. The lemur dentition is heterodont (having multiple tooth morphologies) and derives from an ancestral primate permanent dentition of . Indriids, sportive lemurs, the aye-aye, and the extinct sloth lemurs, monkey lemurs, and koala lemurs have reduced dentitions, having lost incisors, canines, or premolars. The ancestral deciduous dentition is , but young indriids, aye-ayes, koala lemurs, sloth lemurs, and probably monkey lemurs have fewer deciduous teeth.
What Is to Be Done? (Tolstoy) the same Biblical reference (Luke 3:10–14). What Is to Be Done? (Tolstoy) What Is To Be Done? (sometimes translated as What Then Must We Do?) is a non-fiction work by Leo Tolstoy, in which Tolstoy describes the social conditions of Russia in his day. Tolstoy completed the book in 1886, and the first English language publication came in 1887 as What To Do?. A revised translation with the current title was published in 1899. The English title was also used for two better-known works by Nikolai Chernyshevsky and Vladimir Lenin; Tolstoy's Russian title is similar but not identical to Chernyshevsky's