NOTES ON THE DEVELOPMENT OF THE NEWT. 587 
maxillary branch of 5th nerve. VII post-br. Post-branchial branch of 7th 
nerve. YX post-br. Post-branchial branch of 9th nerve. VII pre-br. Pre- 
branchial branch of 7th nerve. IX pre-br. Pree-branchial branch of 9th 
nerve. z. Fusion of 7th nerve with epiblast of gill-cleft, 
Fies. 1—7.—Series of transverse sections through an embryo, to show 
the relations of the post-anal gut to the hind-gut; Fig. 1 being the most 
anterior, and Fig. 7 the most posterior. 
Fig. 1. A little in front of the blastopore, to show the origin of the 
post-anal gut from the hind-gut. 
Fig. 2. Showing the post-anal gut completely separated from the hind- 
gut. 
Fig. 3. Through the blastopore. 
Fig. 4. Behind the blastopore. 
Fig. 5. Showing dilatation of the solid post-anal gut near the hind end 
of the tail. 
Fig. 6. Showing fusion of the post-anal gut with the notochord and the 
neural canal. 
Fig. 7. Showing fusion of the mesoblast with the other layers near the 
extreme end of the tail. 
Fics. 8—11 are taken from one series of transverse sections through the 
anterior end of an embryo, to show the origin of the stomodzeum, the pitui- 
tary body, and thyroid body. Fig. 8 being the most anterior, and Fig. 11 the 
most posterior. 
Fig. 8. Showing the origin of the stomodeum and pituitary body, and 
the fusion of the former with the anterior wall of the fore-gut. It 
also shows the root of the fascio-auditory nerve, and its ventral fusion 
with the epiblast. 
Fig. 9. Showing the hind end of the stomodeum, 
Fig. 10. Showing the anterior end of the thyroid body as a solid rod of 
cells attached to the ventral wall of the fore-gut. 
Fig. 11. Showing the thyroid body near its posterior end. 
Fic. 12.—Longitudinal vertical section through the head end of an embryo, 
to show the origin of the stomodseum and pituitary body as a solid ingrowth 
of epiblast in front of the fore-gut. 
Fie. 13.—Transverse section through the trunk of an embryo shortly after 
the closure of the medullary canal, to show the neural ridge. 
Fic 14.—Longitudinal vertical section through the head end of a somewhat 
older embryo than that from which Fig. 12 was taken, to show the relations 
of the stomodzum and the pituitary body to the fore-gut, infundibulum, and 
notochord. 
Fig. 15.—Transverse section through the trunk of an embryo shortly before 
the closure of the medullary canal, showing the epiblast continuous dorsally 
with it. 
