502 J. I. WILSON AND J. P: HILL. 
since the period represented by Stage 1V. This anterior seg- 
ment of the lamina now exhibits an attenuation of its “ neck,” 
while its fundus shows a very definite oval enlargement, which 
disappears as the anterior plane of 7; is reached. Here, as in 
the preceding stage, the lamina is continuous with the “ re- 
sidual” lamina by the lingual side of that tooth. 
The first incisor is a large pointed germ, with a fairly thick 
dentine sheath to the papilla. The milk incisor, di; (fig. 66 a) 
is present as a strongly calcified miniature tooth, placed at 
the labial side of the apex of 7. It has a small but distinct 
dermal papilla, and the dentine shell is surrounded by a sheath 
of small epithelial cells, which is attached by a laminar con- 
nection to the root or attached border of the dental lamina 
beside 23. 
As in the preceding stages, 73 occupies a markedly labial 
position, and owing to the kink of the lamina, whose occur- 
rence has been already described, its anterior portion has come 
to lie opposite the posterior end of the large iz. Posteriorly 
it occupies a similar position with reference to nearly the 
whole of tz. Indeed, in a few sections all three germs are 
visible in the same coronal plane. Both iz and 7z possess 
dentine caps, and end behind in nearly the same coronal plane, 
though iz extends a trifle more posteriorly than 73. The con- 
tinued dental lamina is, however, placed beside zz, the mor- 
phologically posterior member of the series. 
A long though attenuated residual lamina appears by the 
lingual side of 7;, projecting far beyond the connecting bridge 
between the latter and the dental lamina (fig. 66, rd/.). The 
residual lamina is also present beside zg and iz, but, owing 
to the dislocation of iz, the lamina has undergone corresponding 
dislocation and is partly interrupted. As already indicated, 
it is resumed beside the posterior end of 73, from which it 
extends backwards. 
A delicate epithelial lamina is to be seen springing from 
the root of the dental lamina (i.e. from its attachment to the 
oral epithelium) opposite 7g and 73, and extending labially to 
i, This ends in a minute mass of cells, and it persists through 
