ORGAN OF TASTE IN MAMMALIA. 191 



lose, and in most the papillae offer the three conditions called 

 • conical,' fig. 150, * fungiform,' fig. 149, and * fossulate,' fig. 148,/. 



The tongue is well developed and freely movable in all 

 Marsupials, and the epithelium covering the conical papillae is 

 rarely condensed into spines. In the carnivorous species, as the 

 Datyuri, the conical papillae are minute and soft, but directed 

 backward, so as to give a slight roughness to the tongue when 

 stroked in the opposite direction : under a lens they appear like 

 fine shagreen. Near the base of the tongue in Dasyurus viver- 

 rinus there are three fossulate papillae, in triangle, with the apex 

 toward the epiglottis. A small fibrous or sclerous rudiment of the 

 ' glosso-hyal,' called ' worm,' or lytta, lies lengthwise beneath the 

 tip of the tongue. In the Perameles, besides the minute and gene- 

 rally diffused simple papillae, there are fungiform ones, of larger 

 size, placed at distances of nearly a line apart, and raised about a 

 third of a line above the surface of the dorsum. The fossulate 

 papillae correspond in number and arrangement with those of the 

 Dasyures, but the entire tongue is relatively longer and more 

 slender, especially in Per. lagotis. In some species of Opossum, as 

 Didelphys Philander, the margin of the tongue is fringed with a 

 series of fine long papillae. In Didelphis virginiana the conical 

 papillae of the fore part of the dorsum are retroverted and sheathed 

 with hard epithelium. In the Phalangers there is a thickening at 

 the edge of the fraenum linguae, but no true lytta: the dorsal 

 papillae resemble those of the Dasyures, but are somewhat more 

 obtuse. In the Kangaroo there is a callous ridge along the 

 middle of the under surface of the free extremity of the tongue, 

 and a corresponding furrow along the dorsum ; the latter is 

 common to all the Marsupials. In the Wombat and Koala the 

 dorsum of the tongue rises somewhat abruptly from a furrow 

 surrounding its base ; its form is narrow, moderately deep, dimi- 

 nishing in this respect to the tip, which is rounded. In both the 

 Kangaroo and Koala there is a single large fossulate papilla near 

 the base of the tongue. In Dendrolagus there are three such, 

 arranged in a triangle with the apex turned forward. 



Most Rodentia show two well-marked divisions of their usually 

 deep and compressed tongue : an anterior, which from its vascular 

 and papillose surface is the main seat of taste, and a posterior or 

 intermolar tract, which rises somewhat abruptly above the level 

 of the preceding and brings the food to that of the triturating 

 surface of the molar?. 



The tongue seems to fill the narrow mouth of Rodents more 

 compactly than usual, commonly bearing the impress of the 



