DEVELOPMENT AND SUCCESSION OF TEETH IN PERAMELES. 519 
It is noteworthy that, in respect of its enamel formation, 
dp in Perameles displays a striking degeneracy. At no 
time do the cells of its inner enamel layer attain any great 
degree of elongation as compared with those of other teeth, 
and the layer of enamel actually formed is a very thin lamella 
indeed. 
The Anlage of p2 with its distinct though small papilla is 
well represented in fig. 73. 
In the molar region the residual dental lamina has prac- 
tically disappeared from the first molar, but it is present by 
the sides of m2 and of m2, in which latter situation it is shown 
in fig. 71. 
This section passes through the plane of the hinder end of 
m3, which lies considerably to the labial side of the part 
figured. It will be observed that the connective tissue shows 
a definite concentric arrangement around the residual dental 
lamina in this figure. Such an arrangement persists through- 
out the whole extent of the residual lamina, though it is only 
considerably behind the plane figured that it constitutes the 
Anlage of m4. 
Lower Jaw.—The first two incisors have already completely 
broken through the epithelium at their apices. The anterior 
primary cusp of 72 is just in process of eruption, and here there 
may be observed at its tip a follicular or nest-like arrangement 
of epithelial cells which is in the act of opening out on the 
surface by disintegration, as was noted in the case of dp> in 
the upper jaw. 
di; is still observable, but it is now more degenerate in 
character, merely consisting of asolid dentinal nodule, in which 
no trace of a papilla or cellular core can be recognised. 
dp; is in process of eruption, and this is associated with cell- 
nest formation between the surface and the erupting tooth 
point. The Anlage of p; resembles that of the upper jaw 
pretty closely. 
The fourth molar is a simply but deeply papillated enamel- 
organ with the middle layer of stellate tissue well developed. 
A residual dental lamina has already appeared lingually as a 
