46 
MR. C. S. TOMES ON the structure and 
Fig. 11. Fine tubed dentine, with capillary canals interspersed in it, X 90. Serrasalmos. 
Fig. 12. Transverse section of hardened and decalcified tooth and tooth-pulp, near to 
the base of the tooth, X 60. Lepidosteus oxyrrhinus. The radiating pro- 
cesses of pulp, each coated with odontoblasts, surround a central coarse 
meshed connective tissue framework (p). 
Fig. 13. Tooth consisting of osteo-dentine, X 35. Common Pike, JEsox Indus. A 
thin layer of fine tubed dentine (d) surrounds a central core of large 
channeled bony tissue. 
Fig. 14. One of the larger canals of a Pike’s tooth near to the surface, showing then- 
connexion with the fine tubed layer (f) external to them, X 120. 
Fig. 15. Section of developing tooth and dentine pulp of a Pike, X 30. From the 
first formed layer of hard dentine (d), run down trabeculse (h) of rapidly 
calcifying tissue, which permeate the whole thickness of the pulp. No 
odontoblasts exist during this process. 
Fig. 16. Trabeculse from same specimen, X 200. Cells like osteoblasts (i) clothe 
their surfaces. 
Fig. 16'“ and 16'“"“. Transverse sections, somewhat diagrammatic, of a developing tooth 
of a Pike 16*) and of a Hake (16'“"“'). These show the even contour of the 
pulp forming vaso-dentine and the irregular contour of that forming osteo- 
dentine. 
Fig. 1 7. Base of extruded (d) and upper part of implanted portion (d') of tooth. 
Longitudinal section, X 50. Chrysophrys. The section not being true to 
the long axis of the tooth, the implanted portion appears solid, which it is 
not, having a central pulp cavity continuous with that of the upper part. 
At the junction of what might be termed crown and root the structure 
abruptly changes, fine tubed dentine above giving place to a tissue per- 
meated by large channels (d'). 
Fig. 18. Base of implanted portion of tooth, transverse section, X 30. Chrysophrys. 
The vascular dentine of the exterior is in the interior replaced by a very 
coarsely reticulated calcified mass (d"). 
PLATE 5. 
Figs. 19 and 20. Transverse section of teeth of Chrysophrys just at the junction of the 
implanted portion with that above the gum. The transition from the one 
type of structure to the other is abrupt. 
Fig. 21. Portions of the vascular dentine more highly magnified. Chrysophrys, X 200. 
Fig. 22. Dentine close to the point of transition, from fine tubed to vascular dentine. 
Chrysophrys , X 70. 
Fig. 23. Developing teeth of Sargus ovis. On the left is a tooth just moving into place, 
on the right is a younger one. 
