I.] THE FROG. 59 



y. The urostyle; its body is cylindrical in section 

 and largely filled with a gristly core, identical 

 with ft, which is continued back as a free termi- 

 nation to the whole axial skeleton. 



3. The neural canal; note especially its termina- 

 tion in a pointed extremity, lying within the 

 arch of the urostyle. 



c. Isolate the third vertebra, and examine 



a. Its zygapophyses ; cf. Sect. 2. c. Each is capped 



in cartilage, in common with the other articular 



faces. 

 ft. Its transverse processes ; each terminating in a 



backwardly prolonged cartilaginous expansion. 



4. The skull ; dried preparation. 



a. General. Examine from the dorsal aspect; it 

 embraces 



a. The cranium; median and enclosing the brain, 

 sometimes termed the brain-case. 



ft. ^}\. facial apparatus ; the system of outstanding 

 bars, conspicuous as the jaw-apparatus. 



y. The sense capsules. The auditory capsules, 

 paired postero-lateral expansions; the olfactory 

 capsules, similar but less obvious antero-lateral 

 expansions (they are better seen in the wet state. 

 See infra). 



b. Examine the posterior end of the skull. 



a. The large aperture (foramen magnum) in the 

 middle line, leading into the cranial cavity. 



ft. The convex surface (occipital condyle) on each 

 side of the foramen magnum, for articulation 



