PLATES 19 AND 20. 



Illtjstkatiye oe Mh. Macaxistee's Paper " Ox some foems oe the 



LiGAMENTTTM PteETGO-SPINOSUM." 



Vide Proceedings E. I. Acad., Yol. 2, Ser. 2, p. 110, 



\_In all the Figures the letters have the same significance.'] 



E. External pterygoid plate. 



I. Internal pterygoid plate. 



A. Accessory external pte:^ygoid plate (Pig. 12). 



a. Spiaa accessoria (in Pig. 14 a = ligamentiini pteiygo-spinosnm 



accessorium). 

 I. Lower spine on the external pterygoid plate. 

 m. Muscular ridge on the external pterygoid plate. 

 »wm. Middle meningeal artery. 



n. JS^otch between the two teeeh on the external pterygoid plate. 

 0. Poramen ovale, o'. Inner accessory opening thereinto. 

 p. Spina angularis. 



r. Eidge of thickened ossijS.ed ligament. 

 s. Poramen spinosum. 



t. Inner accessory apei^ture into foramen spinosum. 

 u. Upper tooth on the external pterygoid plate. 

 X. Suture on the ossified ligament. 



PLATE 19. 



Fig. 1. Outer view of outer pterygoid plate, adult male, showing a 

 muscular ridge, and well marked, but separate spinse angu- 

 laris and accessoria. 



2. Outer side of right outer pterygoid plate, showing two hinder 



teeth, as well as spinse angularis and accessoria. 



3. Inner side of right outer pterygoid plate, showing a large per- 



foration (/) co-existing with a notch. 



4. Outer view of right outer pterygoid plate, showing a deep 



notch. 



5. Inner side of right pterygoid plates, showing lower and upper 



teeth. 



K. I. A. PROC, SEE, II., VOL. II., SCIENCE. d 



