MOUTH OF MAMMALS. 385 



its preparation for deglutition. An air-breathing warm-blooded 

 animal, which obtains its food, while submerged, by the capture 

 of small aquatic animals, must derive great advantage from the 

 structure which enables it to transfer them quickly to a temporary 

 receptacle, whence they may be extracted and masticated while 

 the animal is floating on the surface or at rest in its burrow. 

 The soft palate is thick, broad, and divided posteriorly into 

 three fimbriated lobes. The pharynx is narrow, and is encom- 

 passed by two posterior processes of the thyroid cartilage, fig. 212, 

 c, c. The long tubular mouth in Echidna, like that in the Ant- 

 eaters, is remarkable for its small orifice, fig. 302. The palate is 

 armed with six or seven transverse rows of strong, sharp, but 

 short retroverted spines. The tongue is long and slender, as in 

 the true Anteaters ; its dorsum is broad, flat, callous, and beset 

 with hard papillae, and the insects are doubtless crushed between 

 these and the palatal spines. As, however, the food undergoes 

 less comminution in the mouth of this Monotreme than in that 

 of the Ornithorhynchus, the pharynx is wider. 



The jaws of the Marsupialia are covered by well-developed 

 fleshy lips ; the upper one is partially cleft in the Kangaroos, as 

 in some Rodents ; the muzzle is clad with hair in Macropus 

 major and a few other species ; but in most Marsupials it is 

 naked, and generally red from the vascularity of the integument. 

 The palate is sculptured with transverse ridges. These are most 

 numerous in the Bandicoots, being fourteen in the Perameles 

 nasuta, and are slightly curved forwards : the roughness thus 

 produced must aid the tongue in retaining small insects. In a few 

 species of Marsupials I have detected cheek-pouches. In the 

 Koala they are wide and shallow, situated one on each side of the 

 upper lip ; the orifice is opposite the first superior premolar, and 

 leads forward above a horizontal fold of the mucous membrane 

 which attaches the upper lip to the side of the premaxillary 

 bone, separating this part of the cheek-pouch from the mouth. 

 In the Perameles lagotis there are also two small fossae, one on the 

 inside of each cheek, about four lines in diameter, and lined by a 

 very distinct white epithelium. The aquatic Opossum {Didelphys 

 Yapock) has large cheek-pouches, extending far back into the 

 mouth, in which, like the Ornithorhynchus, it may stow away 

 fresh-water insects, Crustacea, &c. The fauces are wide in the 

 zoophagous, but narrow in the entomophagous and phytophagous 

 Marsupials. The tonsils are represented by a pair of small glan- 

 dular cavities. 1 



1 xx. vol. iii. p. 81. 

 VOL. III. C C 



