194 



ANATOMY OF VERTEBRATES. 



142 



into numerous minute wavy or subparallcl folds. The root of 

 the tongue, in Hypcroodon, shows many pores of glandular 

 follicles, anterior to which are four large fossulate papillrc, with 

 a few obtuse conical papillae at the sides : a similar structure 

 here occurs in the tongue of the Cachalot, which Hunter compares 

 to ' a feather bed : ' but the comparison is more applicable to that 

 in the whale-bone Whales : for the tongue is firmer and more 

 muscular in the Cachalot and other toothed Cetacea, than in those 

 with baleen. Most Cetacea offer a marked contrast to the other 

 Mammals in having the skin of the tongue separated from the 

 flesh by a layer of blubber. As a rule, in Mammalia, the vas- 

 cular and sensitive lingual membrane adheres as closely to the 

 muscular tissue as does the very similar skin of the snail : its 

 sanguine tint in Balaenidae is not obscured by pigment: but in 

 some DelphinidcR this is present of a leaden colour. 



In Sirenia the tip of the tongue, fig. 142, a, projects a little 



more freely, but does not 

 reach the fore part of the 

 mouth : the tongue is nar- 

 rower in proportion to its 

 length ; but is chiefly re- 

 markable for the excess of 

 development of the epithe- 

 lium. In the Duo-ono* this 



~ o 



covering of the conical pa- 

 pillae at the fore part of the 

 dorsum gives it the appear- 

 ance of being beset with spines. A large, but short thick, retro- 

 verted horny process projects from each side of the base of the 

 tongue, ib. b, b. The conical papillae in Manatus have a less firm' 

 epithelium, and are longer and finer than in the Dugong ; they 

 are limited to the apex and part of the dorsum. The fossulate 

 papillae are numerous, extending on each side the dorsum from 

 the anterior third to near the base of the tongue. The lingual 

 epithelium appears to have reached the maximum of develop- 

 ment in the now extinct boreal Manatee (Rhytina Stelleri). 



The tongue of the Elephant is tied down, as in the Cetacea, and 

 a part of the dorsum is made by muscular action to represent the 

 tip when it projects : in relative size to the head it offers the ex- 

 treme contrast to the tongue of the Whale : it is not only short, 

 but narrow, and represents, apparently, the intermolar part of the 

 ioiigue in Rodents. It is, however, eminently gustative : the 

 membrane is highly vascular, with very numerous minute and 



Tuiigue of Dugong (Ilalicorc). 



