THE ALIMENTARY CANAL AND ITS APPENDAGES 
PATATAT ib Gns 
THE mucous membrane of the roof of the mouth is thrown into . 
a more or less marked median ridge—the raphe, and into a 
varying number of paired transverse ridges (7.p., Fig. 95), which 
are especially well developed an- is p.D. 
teriorly near the incisors, but pos- és 
terlorly become flattened out. There 
are five to seven of these transverse 
palatal ridges on each side, and they 
are more developed in the embryo 
and the new-born child than in later 
life, when their primarily regular 
arrangement disappears. Those 
farthest back degenerate, but the Fic. 95.—Patatz or a Human 
aiberiof!ones increase in size and  "™PPY0 47 THE HGHTH MONTH. 
one r.p., palatal ridges ; p.p., papilla pala- 
shift nearer to one another as age tina ; a@l., the later formed alveolar 
advances. In very aged persons ord 
the whole system of ridges may almost, or even altogether, 
disappear. © 
In these ridges which, as has been seen, vary to a great extent, 
we have the representatives of a larger and more numerous series 
met with in many lower Mammals (cf. Fig. 96) (dn Apes there 
are aS Many as ten). They are, as a rule, covered with a tough 
stratified epithelium, and are functional in helping to triturate 
and crush the food taken into the mouth (Gegenbaur). 
Some years ago I called attention to the fact that in the 
embryo Cat these ridges develop as rows of papille, which later 
unite, and I put forward the suggestion that we may be here 
dealing with the remains of palatal teeth handed down even to 
Man. Closer investigation must show whether these papille are 
actual vestiges of tooth structures or only horny growths, such 
