On the dorsum of the slow loris tongue there are three vallate papillae, arranged in an inverted V-shape. They contain abundant plexiform nerves and isolated nerve cells but have many taste buds only in its sides, closely associated with the subgemmal nerve plexus. Some ducts of serous glands locating deeply in this region directly open on the upper surface passing through the papilla. No foliate papillae are observed in the posterolateral region of the tongue, but instead of them is found a papilla of fungiform type, which wholly contains abundant plexiform nerves and has a furrow without serous gland ducts and taste buds. Furthermore, its summit is at the same level as the surface and same as its base in diameter, and has embryonic taste buds. From these neurohistologic characteristics this papilla should be regarded as an interformed papilla between the foliate and the ordinary fungiform papillae. Tongue lyssa consisting of hyalin cartilage and striated muscles innervated with motor end plate and simple sensory nerves seems to play a role as receptive organ of the tongue. Underneath the tongue is found well-developed sublingua, which consists of hyalin cartilaginous skeleton and mucosa but has no taste buds. From segmental arrangement of neurovascular spaces in the skeleton it may be an ancestral structure of the tongue.