NOTES ON THE DEVELOPMENT OP THE NEWT. 257 



Fig. 29. — Transverse section through the head end of a Frog embryo, 

 showing the origin of the facio-auditory nerve as an outgrowth from the dorsal 

 surface of the hind-brain. The thickening of the nervous layer of epiblast to 

 form the ear is also shown. 



FxG. 30. — Transverse section through the posterior part of the trunk of the 

 same Frog embryo shortly after the closure of the medullary canal, to show 

 the neural ridge. 



Figs. 31 — 35. — Transverse sections through the same embryo as that from 

 which Figs. 24 and 26 were taken, but posterior to them. 



Fig. 31. Showing on the right the ganglion and the dorsal and prse- 

 branchial branches of the 7th nerve ; on the left the ear and the root 

 of the 8th nerve, and the 1st visceral cleft. 

 Fig. 32. Showing on the right the ganglion of the 7th nerve ; on the left 



the ear and the post-branchial branch of the 7th nerve. 

 Fig. 33. Showing on the right the ganglion and prae-branchial branch of 

 the 7th nerve ; on the left the ganglion and prae-branchial branch of the 

 9th nerve. 

 Fig. 34. Showing on the right the ganglion and prae-branchial branch of 

 the 7th nerve ; on the left the root, ganglion, and dorsal branch of 

 the 9th nerve, and also the 2nd visceral cleft. 

 Fig. 35. Showing on the right the ear and post-branchial branch of the 

 7th nerve ; on the left the ganglion and post-branchial branch of the 

 9th nerve. 

 Figs. 36 — 38. — Transverse sections through the head end of an embryo, to 

 show the relation of the pituitary body to the fore-gut and infundibulum. 



Fig. 36. Showing the fusion of the posterior face of the pituitary body 

 with the wall of the fore-gut. It also shows the ear and the ventral 

 fusion of the 7th nerve with the epiblast of the dorsal wall of the 1st 

 visceral cleft. 

 Fig. 37. Slightly anterior to the preceding, showing the pituitary body in 

 close contact with the wall of the infundibulum. It also shows on the 

 left side the ear, the ganglion of the 7th nerve, and the ventral fusion 

 of the nerve with the epiblast. 

 Fig. 38. Showing the free tip of the pituitary body in close contact with 

 the wall of the infundibulum. 



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