First discovered in 1917, the Tarsier has a unique visual system. Prior to that date it was considered mythical.
The eyeball is about the size of a human's but look at the skull size comparison:
The Tarsier can not move his eye, but to compensate he can turn his head 360 degrees.
TAXONOMY
Suborder: Haplorrhini
Infraorder: Tarsiiformes
Family: Tarsiidae
Genus: Tarsius
Species: bancanus, dentatus, lariang, pelengensis, pumilus, sangirensis, syrichta, tarsier
Subspecies: T. b. bancanus, T. b. borneanus, T. b. saltator