536 J. T. WILSON AND J. P. HILL. 
especially in the form of labial outgrowths therefrom. And 
if it could be shown that the continuous residual lamina of 
Marsupials does actually develop regular localised enlarge- 
ments, bud-like or other, by the lingual sides of the enamel- 
organs of the adult teeth,—of similar character to that which 
we have seen to constitute the first rudiment of p3, then the 
modified views of Leche would receive some support. But 
such is not the case. Of definite and regular “ bud-like ” 
swellings, other than expressions of that general and conti- 
nuous marginal enlargement to which we have already alluded, 
we find no trace, unless indeed the production of isolated 
groups of cells and the formation of epithelial “ pearls’? and 
*‘cell-nests”’? during the final disintegration of the residual 
lamina were to be reckoned as such. And in the latter event 
we have shown that no less than seven rudimentary succes- 
sional germs must be held to be present in the region of the 
upper canine of Perameles. 
It is true that the residual lamella is not absolutely even 
thoughout its entire extent, but presents various slight irregu- 
larities and inequalities, both in contour and in the thickness 
to which its free marginal portion attains here and there. 
These, however, never amount to localised swellings, which 
could possibly be spoken of or regarded as in any sense 
differentiated from the lamina. (The mode of origin of p.3 
will receive special attention.) Where local variations may be 
recognised they are extremely indefinite, and their only sem- 
blance of regularity of arrangement results from the fact that 
the level of the free distal edge of the residual lamina is to 
some extent affected by the depths of the enamel-organ, beside 
which it lies ; hence, e. g., it is much deeper opposite the canine 
than beside the last incisor. These differences have an obvious 
and easy mechanical explanation. Nothing further issues 
from the structural condition thus brought about, except 
perhaps a slightly longer persistence of degenerating remains 
of the deeper lamina. 
The view here set forth is not only borne out by our own 
pretty extensive observations, directed with special reference to 
