The skull in proportionate length is intermediate between that of Avahis and indris.
His skin is soft, and clothed in long fine hair; whence naturalists have named him indris laniger.
This genus has only eleven pairs of ribs instead of the twelve of indris and Propithecus.
The genus indris has more pronounced external ears than have the two other genera of the sub-family.
1839, European name for the babakoto, a lemur-like arboreal primate of Madagascar (Indris Lichanotus); the common story since late 19c. is that the name was given in error by French naturalist Pierre Sonnerat (1748-1814), c.1780, from mistaken use of Malagasy indry! "look! See!" Evidently this was what his native guides said when they spotted the creature and called his attention to it.
However, as Hacking (1981) pointed out, Sonnerat was far too familiar with indris -- he described and figured them in detail, and apparently kept at least one in captivity -- for this story to be plausible. Furthermore, endrina is actually recorded as a native name for the indri (Cousins, 1885), and indri could easily be a variant of this name. Although the word endrina is first recorded in Malagasy only in 1835, there is no evidence that it could be a back-formation from the French indri (Hacking, 1981), and it seems implausible that the Malagasy would adopt an erroneous French name for an animal they were them selves familiar with. [Dunkel, Alexander R., et al., "Giant rabbits, marmosets, and British comedies: etymology of lemur names, part 1," in "Lemur News," vol. 16, 2011-2012, p.67]