CK oss m:\Ks. 



and the ( 'nrnish ehnu^h huilds, I know, all 

 chalky dills of tin- Sussex shore. 



\\liicli (lie louer jaw is :i ft iculaled, in inn I oilier I. ml i IODM 

 \\li;il linear iVnni hefore hackuaids, :iinl rum pi essed ;il I lie sides, 

 admilliu;; vertical motion only upwards and ilm\ mv.mls ; the 

 same process in llie no, hill is spherical. The cavily in ihe 

 lower jau , destined lo icceive this process, is a hollow circnlai 

 cup. The union of these I \\ o portions, therefore, forms an arti- 

 culation possessing the universal motion and Ilex ihilil y of I lie 

 mechanical hall and socket joint. The louer jaw is of #rt'{lt 

 strength, the sides or plates elevated, u it h pioininent coronoid 

 processes, to \vhich, as \vell as lo the whole outi r sides of ihe 

 (he temporal muscle ] a 1 1 ached ; and ina head of (his 

 hird, whii h had been divesled of all Ihe sofl part", I found, oil 

 Sliding the lower laterally upon the upper, as performed hy ihe 

 hird, that, hefore the coronnid process is brought into conlacl 

 with the pleryi^oid, on its own side, the extreme points of the 

 mandildes \v ei e separated laterally to the extent I have already 

 mentioned of .' .'Illi of an inch. The temporal and pyramidal 

 mil ,i li , on III'- rij-lil side of the Ins-id (that heiii;^ the ide lo 

 which the lm\er jaw inclined,) were considerahly larger lhan 

 those of the left, and indicated hy their hulk the 

 power this hird is capahle of exeriin", lo he hereafter noticed. 

 The unusually lar^e ,si/e of the plei y.-MJid muscles, on each ide, 

 ry con .picuous, the space for them heiii" ohlained hy ihe 

 distance! to which the articulated extremities of the lower 

 jaw were removed ; and the food of the hird hein. 

 rendered a narrow pliarvnx : iillicient for I he purpose of SWallov. - 

 ititf. The muscles depressim/; the htwer mandihle are I hree in 

 ninnl "r, only one of which, the greater pyramidal, is vi 

 This sti on" inn ch- covers two olhei small one-, the triangular 

 and .(jiiaie mn-.cles, so called from their particular shape. TheHC 

 three mil ele-,.ill of which have their origin in the occipital por- 

 tion of Ihe cranium, are inserted hy strong tendons on the under 

 and had. of each extremity of the lower jaw, hehind the ci ntre 

 of motion, and, consequently, hy their simultaneous contraction, 

 iai t lh< point lo which they are allached, -md depress I he ante 

 rior part (d'the mandihle. The lower OKI lions of the os a -pia 

 di'ala are pushed somewhat, forwards hy thi, coii,j 



hy two : mall muscle.; one of these, a small Mat muscle, 

 fiom the -eptiim of the oihils, hehind the s-mall aperlii,'<- 

 'd in the seplum, and pa8B6S dow n v> a t d s to he i:, 

 upon the proj'-ctin- slyloid pi o of I he os <piadral um. 'J'he 

 K 2 



