MOUTH OF MAMMALS. 395 



The back of the mouth, in Ruminants, presents its chief modi- 

 fications in the Camel-tribe. A broad pendulous flap hangs down 

 from the fore part of the soft palate and usually rests upon the dor- 

 sum of the tongue. The velum palati extends beyond this process, 

 some way down the pharynx and terminates by a concave border. 

 The pharynx behind the velum dilates into a sac. In the rutting 

 male the palatal flap is greatly enlarged. I have found it extend- 

 ing ten inches down the pharynx, passing below the margin of the 

 soft palate and the opening of the larynx, into the O3sophagus : in 

 the living animal it is, at this season, occasionally protruded, with 

 a belching noise, from the mouth. Its surface shows the pores of 

 innumerable mucous crypts, and in the ordinary state, in both 

 sexes, the flap may apply its own secretion, and water regur- 

 gitated from the storage-cells of the stomach, to the extended 

 surface of the pharynx and root of the tongue, so as to allay the 

 feeling of thirst and help the animal to endure the long remis- 

 sions of drinking to which it is liable in traversing the desert. 



The mouth in Carnivora is characterised by the width of its 

 gape, and the mobility, dilatability, and contractility of its mus- 

 cular and membranous walls. Cheek-pouches have not been 

 found in any species. The great extent of faucial membrane 

 between the back of the tongue and the larynx, with the coex- 

 tensive soft palate in the Lion and some other large Felines, 

 has been adverted to (p. 198); also the retroverted spines, and 

 the lytta of the tongue in connection with the work of the mouth, 

 in certain Carnivora. In the Hyasna the tonsils are relatively 

 larger than in the Lion. The palatal gum is transversely ridged 

 in most Carnivora. The provision for the lubricating mucus at 

 the back of the mouth and fauces is much less in the present than 

 in the hoofed group of Mammals. 



In Quadrumana the Cercopitheci, Macaci, and Cynocephali 

 have cheek-pouches, the slit-like orifices of which are a little 

 within the labial commissure ; the cavity extends outside and 

 below the mandibular rami, where it is occasionally seen much 

 distended with food. The Semnopitkeci and Colobi, remarkable 

 for their large sacculated stomachs, have not such cheek-pouches : 

 they are wanting also in Lemuridce, Platyrhines, and tailless 

 Apes. 



The Lemuridce have the palatal gum ridged. In the Aye-aye ' 

 there are three curved transverse ridges anteriorly, convex for- 

 ward, followed by four transverse pairs of similar ridges. In 

 other Lemur idee the palatal ridges are similarly curved, but 



1 en', p. 41, pi. xii, fig. 6. 



