70 ' Mammalia. Digestive System. ^ 



two ridges, just anterior to tlie angle of the jaw, which become 

 very callous, and seem to occupy the place of teeth : in Myrmeco- 

 phaga Didactyla they form horny plates. 



6. Palate. 



In Bimana and the higher Quadrumana the Palate is smooth and 

 unridged. 



Rodentia. The roof of the mouth is commonly beset posteriorly 

 with two rows of hard oblique ridges, and in Capromys three hard 

 tubercles are found anteriorly. In Capybara the constriction of 

 the soft Palate reduces the communication between the mouth and 

 pharynx to a small aperture. 



Artiodactyla. In the Camelidae a broad pendulous flap hangs 

 down from the fore part of the soft Palate, and usually rests upon 

 the dorsum of the tongue, though it is sometimes greatly enlarged. 

 Its surface shows the pores of innumerable mucous crypts : the 

 secretion these provide aids in keeping the surface of the pharynx 

 and root of the tongue moist when water is scarce. The back of 

 the mouth appears to be as completely closed in the Giraffe as in 

 Capybara. 



Monotremata. In Ornithorhyncus the soft Palate is thick, broad, 

 and divided posteriorly into three fimbriated lobes. In Echidna 

 the Palate is armed with six or seven transverse rows of sharp short 

 retroverted spines. 



7. Uvula. 



Bimana. The Uvula is almost characteristic of the Order. 



Quadrumana. In the Catarrhina a short Uvula is apparent. In 

 the Platyrrhina the fauces are but slightly divided. In the Le- 

 muridae there is sometimes found* a median longitudinal fold from 

 the back of the soft palate close to the margin, but this never pro- 

 jects so far as to divide the fauces into two arches. 



In-Enamellata. In Dasypus 9-cinctus the soft palate is thick- 

 ened in the middle, like a rudimental Uvula. 



8. Tonsils, 



Rodentia. The Tonsils are perhaps the most feebly developed in 

 this Order. 



e.g. in Aye Aye. 



