564 J. T. WILSON AND J. P. HILL. 
29 (a”) may be recognised, one above the other. It is plain 
that, whatever be the real meaning of these, it is impossible to 
regard them as vestigial representatives of teeth. This form 
of labial projection must therefore be excluded. Again, it may 
be found that a projection on the labial side of the dental 
lamina is traceable to the point of severance of the lamina 
from the oral epithelium. 
Thus in the section shown in fig. 27, an outgrowth of this 
character (“ b”) appears to be the direct prolongation of the 
proximal margin of the dental lamina, which has just been 
separated from the oral epithelium though it is still in contact 
with it. If a comparison of this figure be made with that of 
dp2. in fig. 24, it will become evident that the condition in the 
former is easily derived from that of the latter. We have only 
to imagine that the freed margin of the lamina in the region 
of m+ has become shifted, or has actually grown, labially from 
its late point of attachment (or later point of severance). Such 
an explanation may possibly apply not only to the case quoted, 
but to that represented in Woodward’s fig. 26, m’ (cf. also his 
fig. 20, d. 1.). 
On the other hand, neither of the explanations suggested 
above appears sufficient to account for the appearance shown 
in his figs. 25 a, and 25 6. These represent a form of out- 
growth or projection with which also we are familiar in Pe- 
rameles. Thus in figs. 30 and 31, passing through the lamina 
just behind m+ in Stage 111, and where the last trace of the 
enamel-organ of that tooth is disappearing from the sections, 
we find that a labial process (/. 0.) of very distinct and definite 
character manifests itself, springing from the neck of the 
dental lamina. This becomes established, not as a mere local- 
ised projection, but as a continuous secondary lamina 
extending right back to the place where the entire dental 
lamina ends abruptly in the Anlage of m2 (figs. 25-6). 
The structure described cannot, we believe, be explained by 
either of the modes of interpretation already put forward as 
applicable to some other cases. It cannot in any sense be a 
consequence of disintegration or severance, and its constancy 
