I.] THE. FROG. 67 



iii. The foramen \ of exit for V. VI. VII.; a large 

 aperture, below and in front of the pro-otic. 



iv. The foramen for IX. and X.; perforating the 

 body of the exoccipital. 



v. The auditory foramen (VIII.); a small per- 

 foration of the cartilaginous wall of the audi- 

 tory capsule just behind iii. 



vi. The foramen for III.; small and situated im- 

 mediately in front of iii. 



vii. The foramen for IV. (n. patheticus) very 

 small, above and a little in front of the optic 

 foramen. 



/. The mandible. See 4. e. ft. 



Strip off the dentary with care; there will be 

 found, in close apposition with the outer face of 

 the angulo-splenial, 



a. Meckel' s cartilage ; a gristly rod, forming a core 

 for the lower jaw. Examine its posterior end ; 

 it is alone concerned in articulation. 



(3. The mento-Meckelian bone ; a small nodule aris- 

 ing as an ossification of the symphysial end 

 of a. 



6. The hyoid. 



a. Its broad somewhat tetragonal central part (body), 

 bearing a number of outstanding processes, for 

 attachment of muscles (cf. Sect. E. 2. c.}. This 

 is usually cartilaginous, being ossified only in old 

 individuals. 



/'. Its posterior cornua, or thyro-hyals ; short bony 

 rods, sloping obliquely backwards and outwards. 



52 



