DEVELOPMENT AND SUCCESSION OF TEETH IN PERAMELES, 463 
cated close to the anterior extremity of the lamina by the 
presence of a subglobular outgrowth (i+), bulging in an an- 
tero-lateral direction, i.e. at right angles with the axis of the 
lamina (d/’.)in this situation. The lamina itself is here plump 
and swollen, so that on section the two together form a bilobed 
mass. The labial lobe, however (“7+ ”’), is merely a localised 
swelling, while the lingual (dl.), becoming more attenuated 
behind, is continued for some distance onwards to connect 
with the second incisor region. 
It will be remembered that, in the preceding Stage 11, i+ 
was represented by a mere uniform enlargement of the dental 
lamina. The outgrowth of the labial mass we have now de- 
scribed constitutes therefore the next step in the differentia- 
tion of the enamel-organ of the first incisor. And the growth 
of this labially projecting mass involves the development, 
between it and the main body of the lamina, of a depression. 
This is seen both in front, behind, and especially above, where 
it is somewhat more pronounced. The surrounding capsule of 
connective tissue, where that is in relation with the depression 
in question, exhibits distinct though slight evidences of cel- 
lular differentiation. Fig. 16 shows a horizontal section of 
the first incisor region with the sulcus extending on to the 
anterior face of the Anlage. Here the connective tissue is 
less fibrous, and its cells are more closely aggregated to- 
gether to form what is in all probability the Anlage of the 
dermal papilla. The latter indeed projects slightly into the 
sulcus. 
The formation of the labial lobe above referred to, and the 
associated production of a depression between it and the main 
portion of the dental lamina, are of great importance. We 
find that when the earliest stage of the process of cupping of 
an enamel-organ can be traced, that process is commonly, if 
not invariably, initiated by an overgrowth of the cells of the 
dental lamina so as to form a projection on the labial aspect ; 
and that the future cup-like depression into which the dermal 
papilla subsequently fits is foreshadowed by such a sulcus as 
we have above described. And when the cupped enamel- 
