THE SKULL. 31 



bone : the third or lower arm (/ 3 ), supported by a cartilage l , runs 

 backwards and downwards to unite with the side of the broad 

 hinder extremity of the quadrato-jugal bone. 



The cartilaginous basis 1 of the suspensorium (Fig-. 17 #//, //) is a 

 direct continuation of the cartilaginous basis of the cranium, and 

 proceeds from it to the outer extremity of the prootic ; from this 

 point the cartilage runs backwards and divides into two branches ; 

 of these, one (*//) retains the original course backwards and 

 outwards towards the articulation of the lower jaw, and in con- 

 junction with the quadrato-jugal (j) forms this joint. The other 

 (*//') is directed forwards along the anterior arm of the pterygoid 

 bone ; it widens in front (sn), and becomes directly continuous with 

 the cartilaginous strut described above as projecting from the 

 hinder part of the cartilaginous olfactory capsule. 



8. The quadrato-jugal bones, o*f;a jv.tjalia, Cuvier (Figs. 10, 



Duges, tympano-maUtal. n. n. Cuvier, /. c.. p. 399, PI. XXIV, Figs. 

 j, 2 o. Hallmann, quadrato-jugal bone, /. c., p. 39. Parker and 

 Bettany, I. c., quadrato-jugal. 



This is a small process of bone, likened by Duges to a comma, 

 which rests by its posterior broader extremity on the cartilage of 

 the mandibular arch *, and forms with it a portion of the articular 

 head for the lower jaw. The anterior extremity is pointed, directed 

 forwards, and attached by ligament to the maxillary bone. 



9. The pterygoid bones, oua ftTygoidea(\g&. 10, i i,ij,iqpf). 



Cuvier, I.e., p. 389. PL XXIV. Figs. i. 2 m m. Duges, n. 9. Parker 

 and Bettany, /. c., pterygoid bones. 



These bones, shaped like the Greek letter A, possess each three 

 arms : of these the middle one is attached to the under surface of 

 the prootic bone by a cartilaginous process (Fig. 18^;); the hinder 

 grooved arm lies upon the under surface of the cartilaginous suspen- 

 sorial arch (Fig. 1 8 *//) ; and the anterior arm (pt) runs forwards 

 along the inner border of the anterior ramus of the suspensorium 

 ($//')' i n contact with the maxillary, palatine, and nasal bones. 



The cartilage just mentioned, by means of which the middle arm 

 of the pterygoid is connected with the cranium (compare Fig. 18), 

 proceeds from the cranial origin of the cartilaginous arch (sp), 

 turns downwards and then forms a sort of articular head (''ft), 

 which is articulated to an oval flat elevation of the prootic cartilage 



1 This cartilage is the quadrate cartilage of Parker ; others regard it as the upper 

 end of the cartilaginous mandibular arch, of which Meckel's cartilage is the lower 

 distal part. 



