﻿July, 1896.] 



CHARACTERS OF BONY PALATE. 



27 



Until just before acquiring its greatest widtli, the surface of the pal- 

 atine is on the same level ^ith the rest of the bony palate, but imioe- 

 diately on reaching this point it changes abruptly at the sides, more 

 gradually in the median line, to the level of the anterior border of the 

 nterpterygoid fossa, which lies about 0.5 mm. dorsad of the main part 

 of the bony palate. In the median line the palatine slox^es gently dor- 

 socaudad to the edge of the interi:)terygoid fossa, a distance usually of 

 about 1 mm., but at the sides it breaks away suddenly, and the spaces 

 between the median sloping ridge and maxillaries are occupied by con- 

 spicuous pits (fig. 7 A, J.J)). The floor of each pit is continuous with 

 the backward projection of the palatine, which runs out to join the 



Fig. 7. — Palatal view of skull of 2Iicrotus {llicrotus) arvalis (A) and Erot-jmiis gappcri fB). (x3). 

 I. fa., interpterygoid fossa (reference line crosses pterygoid fossa): i.fn., incisive foramen: l.br., 

 lateral bridge: ?. ,'/r.. lateral groove ; Z./^., lateral pir : /•.. niedi:in ridge ; 7/i.r.. maxillary : pL.pU., 

 palatine; prax., premaxillary ; pt., pterygoid (reference line crosses pterygoid fossa i: //i. r., slop- 

 ing portion of median ridge. 



pterygoid of its side {fig. 7 A, pt.). The A'entral outline of the inter- 

 pterygoid fossa (fig. 7 A, i.fa.) forms three sides of a figure, which is 

 nearly a parallelogram, open at one end, the longer axis parallel with 

 the main axis of the skull, and the length more than double the width. 

 In front and for a short distance at the sides the fossa is limited by the 

 palatines (fig. 7 A, but the greater part of its boundary is formed 

 by the pterygoids (fig. 7 X^pt.). The open end lies between the hamu 

 lar i3rocesses of the pterygoids. Extending back from the incisive for- 

 amina are two distinct lateral grooves (fig. 7 A, 1. gr.)^ which traverse 

 the bony x^alate longitudinall}', leaving between them a ridge which pos- 

 teriorly is continuous with the sloping median ridge already described. 

 In these grooves open numerous foramina, larger and more crowded 

 just in front of the region from which the bony palate slopes away to 



