DEVELOPMENT AND SUCCESSION OF TEETH IN PERAMELES. 461 
It is throughout in direct connection with the deep surface of 
the oral epithelium, as serial sections, sagittal and transverse, 
show most definitely. But as in the upper jaw, so also here, 
there is found at a short interval behind dp.z an outward pro- 
jection or bulging of the labial aspect of the lamina entirely 
comparable to that which in the upper jaw serves to broaden 
the lamina transversely. Here, however, it is placed much 
nearer to the “ neck ” of the lamina, and throws a very slightly 
cupped surface, with the rudimentary papilla in relation to 
it (mp.m;z), more distinctly on to the labial aspect of the 
Anlage. Fig. 15 illustrates the condition described, and may 
be advantageously compared with the figure of the lower 
canine Anlage (fig. 13). 
Behind the Anlage of m; the labial projection disappears, 
and the lamina is left as a simple but fairly thick band lying 
parallel with the oral epithelium, to which it is attached by a 
“neck” curved almost at right angles with the dorso-ventral 
axis of the lamina. As in the upper jaw, this disappears alto- 
gether with considerable abruptness. 
Our readers will thus observe that in following the develop- 
ment of the dental lamina in Stage 11 we have been able to 
trace what to all appearances are the earliest steps in the 
direction of individual tooth-differentiation. During this 
period the dental lamina still includes the Anlagen of all the 
future teeth; none of these have as yet been emancipated 
from it, and the great majority of the Anlagen have as yet 
little or no claim to be considered as individualised tooth- 
germs. 
Regarding the morphological interpretation of our observa- 
tions, especially in the way of the determination of tooth 
Anlagen, we believe that in the case of a number of these 
there can be difference of opinion. It has already been indi- 
cated that the justification of our interpretation in certain 
other cases depends to some extent upon our observations in 
subsequent stages of development. A fuller discussion of 
these more disputable points must therefore be reserved till 
later. 
