I.] THE FROG. 65 



the olfactory capsule. It projects freely for- 

 wards and inwards. 



c. Lateral aspect. 



Compare generally with a. and b. and note es- 

 pecially. 



a. The siispetisoriutn ; its backward rotation; its 

 rounded free end, for articulation of the lower 

 jaw. 



yS. The quadrate bone; represented by an insig- 

 nificant nodule lying within the substance of a. 

 near its articular end. It may or may not be 

 confluent with the quadrato-jugal. 



d. Posterior aspect. 



a. The exoccipitals ; separated above and below 

 by cartilage (i.e. there are no median occipital 

 bones). 



y8. The coliwiella aiiris. Remove this on the dis- 

 sected side ; and note that its inner end plugs a 

 large aperture (^fenestra ovalis) in the outer wall 

 of the periotic capsule. 



y. The siispeiisoriiim ; now seen, on the same side, 

 in its entirety. Note ; its pedicle^ the main bar, 

 prolonged down to give articulation to the lower 

 jaw; its dorsal cross, confluent with the outer 

 wall of the auditory capsule, and expanded, to 

 form a ledge {tegmen tynipani) which overlies 

 the columella; its ve?ttral cross (cf. b. yS.) rounded, 

 and in definite articulation with the antero- 

 ventral border of the auditory capsule. 



e. Inner aspect. 



Remove all that remains of the chondro-cranium 

 M. c 



