THE SKULL. 



35 



outer surface of the anterior half of the angulosplenial, and articu- 

 lates in front with Meckel's cartilage ; it is a thin, flat lamella of 

 bone ; (3) in the groove of the angulosplenial is found a cartilag-e 

 occupying- its entire length (A 4, JS 4), Meckel's cartilage ; it is 

 broader behind, and here forms the articular fossa of the lower jaw; 

 anteriorly it is covered by the dentary, and articulates with the 

 (4) mentomeckelian (A 3, B 3) at its anterior end, which is bound to 

 its fellow of the opposite side by ligaments, and unites the two 

 halves of the lower jaw. 



The upper part of MeckeFs cartilage, which forms the joint with 

 the suspensorium, must be regarded as the articidare ; to this also 

 belongs the anterior, ossified portion of the mentomeckelian ^ ; the 

 dentary, which covers MeckePs cartilage, must represent the os 

 dentale ^ ; the first and largest bone, the angulosplenial, which lies 

 on the inner side of the cartilage, must be considered as the os oper- 

 ciilo-angulare, Dugès, for it contains the elements of these bones. 



rTe. 



22). 



16. The hyoid bone, 0* liyoideum (Fig. 

 Parker and Bettany, I.e., hyoid. 

 This consists of a broad, thin, cartilaginous plate, w4th processes 

 passing from it as represented in the figure. We distinguish in it : — 



(a) the body (7Z), somewhat oblong, and 

 wider in front than behind. From the 

 anterior angles there projects on either side 

 a bkmt rounded process (//) ; from either 

 posterior angle a more pointed process (//'). 



(b) The anterior cornua (^') [cornna sh/- 

 loided) project from the anterior border of 

 the body, first in a forward direction, then 

 in a curve backwards and upwards (compare 

 Fig. 12). to unite with the cartilage of the 

 prootic bone. Where the direction of these 

 cornna is changed each sends off a short 

 blunt process, (c) The posterior cornua 

 {cornna thyroidea) {II") are bony rods which 

 run from the hinder margin of the body, diverge posteriorly, and 

 enclose the larynx. 



Hyoid of Rana csculenta, 

 twice nat. size. 

 // Body ; h h' processes. 

 H' Anterior horn. 

 H" Posterior horn. 



Dugës, OS dentale. 



Dugès, sur angulaire. 



D 2 



