296 
ON THE DEVELOPMENT OP THE TEETH OP THE NEWT, ETC. 
Fig. 9. Apex of tooth, with its enamel cap undisturbed ; the odontoblast layer is also 
seen, x 400. 
Fig. 11. Lip and margin of upper jaw of full-grown frog, with tooth in place and 
to its normal extent, X 50. 
Fig. 20. Young tooth-germ of Lacerta viridis, X400, from the same section, as fig. 18. 
PLATE 47. 
Lettering the same as Plate 46. 
Figs. 10 to 15. Common Frog. 
Figs. 16 to 22. Anguis fragilis and Lacerta viridis. 
Fig. 10. Diagrammatic section of upper and lower jaws of a common frog, X 5. 
Fig. 11. See Plate 46. 
Fig. 12. Successional tooth-sac beneath the tooth in place; enamel-germ very distinct, 
X 120. 
Fig. 13. Successional tooth-sac partly buried in the tooth-bearing parapet of bone, X 80. 
Fig. 14. Relations of enamel-germ to the area of tooth-formation and to the maxillary 
bone, X 220. 
Fig. 15. Young tooth-sac prior to the formation of dentine, X 250. 
Fig. 16. Upper jaw of Angitis fragilis, showing a tooth ascending into position, a succes- 
sional tooth-sac, and the connective tissue to the right of the area of tooth- 
formation, X 40. 
Fig. 17. Lower jaw of the same, X 40. 
Fig. 18. Upper jaw of Lacerta viridis ; to the right of the perfected tooth is a very early 
tooth-sac, X 150. 
Fig. 19. Young tooth-germ of Anguis fragilis, X 500. 
Fig. 20. See Plate 46. 
Fig. 21. Relation of tooth-sac to oral epithelium. The band of connective tissue (m) at 
the top of the bone, which takes a share in cementing on the teeth, is well 
seen (Anguis fragilis). X 150. 
Fig. 22. Apex of a forming tooth ; the odontoblast layer of the pulp, with the dentinal 
fibrils stretching across to the dentine, is well seen, X 300. 
