PLATANISTA. 435 



portion of its structure, wMcli is quite distinct from that of the neighbouring 

 substance of the tongue or of the papillas, in that it has a cellule- granular or 

 glandular character. Projecting from the base there is what appears to me to be 

 an orifice. If this is a glandular structure with an excretory duct, the position 

 which it occupies as a kind of valve at the orifice of the excretory duct of the highly 

 complex mucous gland, would render it probable that the two glands are intimately 

 related to each other. The valvular gland, while performing its special functions in 

 the economy of the oral cavity, may fulfil a secondary function, by closing the 

 mucous gland, the secretion of which, it may be important, should not be excreted 

 along with that of its plug. 



Falate. — This presents two furrows internal to, and parallel with, the upper 

 lips, and into which the lower lips are received when the mouth is closed. The 

 anterior portion of these furrows is marked by fi.ve deep pit-like impressions corre- 

 sponding to the five posterior teeth of the lower jaw. It would thus appear that the 

 surfaces of the mouth are in very close apposition — a circumstance which is also 

 verified by the fact that the tip of the tongue is generally marked by the impression 

 of the two most posterior teeth of the upper jaw, and the postsymphysial space 

 anterior to it is also marked by the impress of the teeth. The teeth of the two lines 

 are not opposite to each other owing doubtless to the asymmetry of the skull, and as 

 the lines are posteriorly divergent and approach each other at the front part of the 

 palate, they are alternate in that region, and immediately external to them are the pits 

 for the teeth of the lower jaw. There are seven teeth on the left and six on the 

 right side. The palatal surface posterior to the teeth is slightly convex, but perfectly 

 smooth. In this same individual, two orifices occur in the palate 6*50 inches posterior 

 to the first tooth above, in the middle line, half an inch behind the posterior border of 

 the pterygoids. These mucous crypts are placed transversely, and are separated from 

 each other by an interval of about 0'25 inch. They are longitudinally oval orifices, 

 O'l inch long, and each leads into a crypt in the mucous membrane, into which 

 small mucous glands open. These orifices I have been unable to detect in an 

 adult. The palate anterior to them and between and posterior to them, is nearly 

 devoid of racemose glands, but these structures are numerous on the margin of 

 the posterior portion of the palate and on the fauces. The soft palate is 1-75 

 inch long in the individual under consideration (54 inches), and its posterior 

 margin is sharp without any indications of an uvula, anterior or posterior pillars, or 

 tonsils. 



Dentition and changes occurring with age. — Sir Everard Home' remarks that 

 the changes that take place in the form of the teeth as they wear away from long 

 use are more remarkable than in most other teeth, for the perfect tooth has a toler- 

 ably sharp enamelled point, while the half- grown tooth has a concave, blunted cut- 

 ting edge. 



These changes in the form of the free ends of the teeth are also associated with 

 a remarkable increase in the size of the teeth. In a young specimen differing in no 



1 Phil. Trans. 1818, vol. 118, p. 418, plate xx. 



