I.J THE FROG. 59 



y. The urostyle; its body is cylindrical in section 

 and largely filled with a gristly core, identical 

 with y3, which is continued back as a free termi- 

 nation to the whole axial skeleton. 



8. 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. 



fi. 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. 



(3. The 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 cai'ity. 



(3. The convex surface (occipital condyle) on each 

 side of the foramen magnum, for articulation 



