DEVELOPMENT AND SUCCESSION OF TEETH IN PERAMELES. 465 
complete the enamel cup, leaving a more or less liberated dental 
lamina independently of the enamel-organ, and situated at its 
inner or lingual side. This we term the “residual dental 
lamina.” 
After this somewhat necessary digression—partly antici- 
pative of what we shall have to point out in detail later on— 
we may return to the description of the lamina in Stage 111. 
Behind the posterior limit of the Anlage of i+ the dental 
lamina becomes itself progressively reduced in sectional area 
until it approaches the region of the second incisor, its axis 
being directed somewhat outwards as well as backwards to 
reach the latter. 
Here it quickly increases both in height and in thickness, 
and is seen to form the lingual portion (d/2) of another 
bilobed mass (fig. 17), comparable to that in the region of 7+. 
To this bilobed swelling a similar interpretation must be given 
as that employed in the case of the first; i.e. its lingual por- 
tion is simply the enlarged dental lamina (d/?), while the 
labial portion of the main mass projecting outwards (“72”) 
is the outer or labial portion of the enamel-organ of 12. Here 
_again the lobes are separated by a groove (fig. 17) passing 
over the summit of the Anlage, and reaching its anterior and 
posterior aspects. 
In fig. 18 “II” represents a horizontal section of the whole 
epithelial mass in the region of the second incisor. Here dl? 
indicates the lingual lobe of the mass corresponding to the 
swollen continuation of the dental lamina itself. This hori- 
zontal section is taken above the level which would show the 
continuity anteriorly of dl2 with dil+ in fig. 16, aud about 
the level indicated by the line ad. in fig. 17, which shows a 
coronal section through the same region. (It will be remem- 
bered that between the developing teeth the dental lamina is 
considerably lower than opposite them.) In this figure of a 
horizontal section there is seen to project from the labial 
aspect of i2 a small epithelial mass (di2), which we believe to 
be the representative of the enamel-organ of the second milk 
incisor. The same projection is visible in fig. 17, showing a 
