ORGAN OF TASTE IN MAMMALIA. 197 



and forms minute retroverted spines, which occasion the rasp- 

 like roughness which is felt in the tongue of the livino- aiii- 



o o 



mal. The upper superficial layer of the lingualis, which acts 

 more directly 011 these papillae, and is by some called ' noto- 

 glossus,' is conspicuously differentiated from the main mass at 

 this part of the tongue. The deeper transverse fibres decus- 

 sate with those of the opposite side, the ' septum albescens ' 

 being but partially present in the tongue of Ruminants. In the 

 Giraffe a dark leaden-coloured pigment is developed beneath 

 the epithelium, covering the anterior half of the tongue, in rela- 

 tion, perhaps, to its frequent exposure, under a tropical sun, in 

 the prehension of the leafy food : the pigment assumes a black 

 colour over the prominent round fungiform papillae, which are 

 somewhat sparingly scattered, like coarse grains of gunpowder, 

 over the dark-coloured portion of the tongue ; from fifteen to 

 twenty fossulate papillae are arranged in an irregular longitudinal 

 row on each side of the raised intermolar part of the tongue. As 

 the organ is mainly a prehensile one, its structures thereto adapt- 

 ing it will be described in connection with the preparatory in- 

 struments of digestion. 



o 



In most Carnivora the septum is complete, and the ' fibrae 

 trans versae ' are firmly attached to it, instead of decussating. The 

 lower margin of the septum is thickened, and in many species 

 includes the long cylindrical fibrous body, representing the 

 f glosso-hyal,' called ' lytta,' and in Dogs, where it attains its 

 largest size, f the worm.' 1 It may help by its elasticity, and that 

 of its sheath, in the act of lapping. In the Seals the apex of the 

 tongue is bifid and fringed with delicate papillae ; they are less 

 marked on the upper flattened surface : towards the base are the 

 ( fossulate papillae,' behind which the lingual membrane is puckered 

 into rugae and beset with numerous follicles. In the Bears 

 the apex of the tongue is entire, expanded, and impressed above 

 by a medial longitudinal groove : the conical papillae are minute 

 and close-set, with soft epithelium : those at the under part of the 

 margins are coarser. In Siwursus Thibetanus with the simple 

 papillae are intermixed small white petiolate papillae : near the 

 base are eleven large fossulate papillae forming two sides of a 

 triangle whose apex is turned backward. The tongue of the 

 Kinkajou (Cercoleptes) shows seven fossulate papillae similarly 

 placed and arranged ; but it has a long and large ( lytta,' liga- 

 mentous anteriorly, cellular posteriorly, in a sheath of circular 

 fibres. 2 



1 sx. vol. Hi. p. 83, nos. Iol4 (JTycena), 1514A (Jackal}. 2 LXXXIF-. p. 122. 



