456 Jw. T. “WIESON- AND rd. “PL HERE. 
(vide fig. 7) from near the basal portion (i. e. the “ neck”) of 
the elongated laminar ingrowth. A comparison with fig. 13, 
which shows the exactly.corresponding structure in the case of 
the lower canine rudiment, will sufficiently demonstrate the 
first steps in that evolution which results in the interesting 
condition so beautifully shown in the next stage, where we 
have the well-formed miniature enamel-organ of a deciduous 
canine tooth above and below (figs. 20 and 37). 
On account of the deep extension of the canine Anlage it 
forms a prominent feature in sagittal sections which pass 
through its plane, all the more that a long extent of the 
dental lamina behind it, though quite continuous throughout, 
is relatively very shallow and insignificant. This latter por- 
tion of the dental lamina, representing the whole of the pre- 
molar region between the canine and the deciduous premolar, 
is at the present stage absolutely void of any special structural 
differentiatiou. It is, as already said, comparatively shallow 
(though a “neck”’ is slightly indicated), and extends back- 
wards through very many sections to the region of dp3. 
Here it again deepens considerably, its deeper part or fundus 
becomes swollen, and ere long it is seen to be deeply indented 
on its labial aspect by a large papilla, giving it the typical form 
of a cup-shaped enamel-organ. This is represented in fig. 8, 
in which it is to be noted that the process of formation of a 
cup-shaped enamel-organ has gone on without any trace, so 
far, of the emancipation of the developing organ from the 
parent lamina. An early stage of the latter process may, 
however, be recognised in fig. 9 (rdl.), which represents the 
corresponding organ in another embryo from the same pouch. 
(For the more advanced stage of the same process compare the 
next stage as illustrated in fig. 24.) 
Special attention may once more be called to the fact that 
although dp= in Perameles is never other than a small and 
insignificant tooth compared with the other functional members 
of the dental series, yet nevertheless at this early stage it is 
already large and well advanced in its development as an 
enamel-organ; and it is the only antemolar tooth-rudiment, 
