554 DE. C. F, SONNTAG ON THE COMPARATIVE ANATOMY 



The vestibule and caviim oris commvinicate through the 

 diastema anteriorly, and^ behind the last pairs of molar teeth 

 posteriorly ; the former of these is wide and the latter narrow. 



The Palate (Plate V., A). — The upper incisor and canine teeth 

 surround a small area on which there are six small tubercles, 

 but these do not cover prominences on the premaxillge. Imme- 

 diately behind these lies the first of the nine palatal ridges, which 

 are most marked anteriorly. Forbes also described nine ridges, 

 and Young recorded eight. Ma,rtin described eight furrows. The 

 anterior ridges are transverse, and are complete or incomplete, 

 but some of the posterior ridges are curved and bear small 

 nodules on their anterior borders. 



When the mucous membrane is removed the bony palate is 

 seen to have a sinuous outline when viewed laterallv (text- 

 fig. 59, E). _ 



The soft palate is long, smooth, and devoid of a uvula. 



The isthmus faiicium (text-fig. 59,/) is a, ciroulax oi'ifice which 

 admits the tip of the index finger, and the fauces form a septum 

 without the tonsils, which lie far back in the pharynx at a 

 distance of 6 cm. from the incisor teeth. 



Trichosurus vulpecula (Plate V., B). 



Cheek-pouches are absent, and the vestibule and mouth com- 

 municate as in the above. On the palatal ai'ea surrounded by 

 the incisor and canine teeth, which form a more perfect arcade 

 tha,n in Phascolarctos, there is a median I'idge and sevei'al small, 

 hard papillae. 



The palatal ridges, of which there are six, are sharper than in 

 PJiascolarctos, and the a.nterior ones are convex forwaixls, with 

 the free edges dii-ected backwards. Between several of the 

 ridges the mucosa is covered with papilkie. 



The tonsils have the usual situation in the fauces. 



Pseudochirus peregrimts (Plate V., C). 



There are eight palatal ridges, most prominent anteriorly, and 

 many papillfe crowd the mucosa between them. Cheek-pouches 

 are absent. 



The Tongue (text-fig. 58). 



Martin (8) states tliat the tongue of Phascolarctos rises abruptly 

 from a furrow surroiuiding its base, and the distance from 

 its root to the epiglottis is ^ of an inch. I found, however, that 

 it is much farther removed, the distance being slightly more than 

 1| inches, a,nd the mucosa of its dorsum is continuous with that 

 of the ventral wall of the pha,rynx (text-fig. 59, A, a). 



Measurements : — Total length 5*5 cm. ; length of the oral 



