NICKERSON — Scales of Lepidosteus. 
Fig. 
2. 
PLATE I. 
Longitudinal section of skin of young gar-pike, 145 mm. long X 140. 
Mucin gland cells of ectoderm ; a-d, stained with Kleinenberg’s hama- 
toxylin; e, stained with Boehmer’s alum hematoxylin, a-d represent 
successively younger stages. X 500. 
Longitudinal section through posterior end of very young scale from fish 
150 mm. long. X 262. 
Optical section of ectoderm, parallel with surface ; from tissue stripped 
off from surface of scales of fish 300 mm. long, after decalcifying 
the chromatophores lie at a deeper level than the gland spaces, and 
therefore appear at different focus. X 110. 
Section from fish 150 mm. long, showing two stages in the formation of 
spine papillae; the section is not quite parallel to axis of larger 
papilla. > 370. 
A part of the section next to that represented in Figure 5, showing 
summit of larger spine papilla and its peculiar shaped secreted tip 
zx is line in which the farther plane of the section cuts the basement 
membrane. 370. 
A longitudinal section through a spine to show the canal connecting its 
central cavity with the exterior. X 100. 
Odontoblast with its process extending into dentinal tubule. From lower 
surface of scale of fish 460 mm. long. X 500. 
Another odontoblast, having two nuclei. Conditions as in Figure 8. 
