562 J. T.- WILSON AND J.-P. HILL. 
And with the development of each successive molar a similar 
condition is brought about. 
It would certainly appear that the evolution of the macropod 
molar proceeds less rapidly than it does in a polyprotodont 
form like Perameles.! In any case it becomes quite certain, 
from examination of our consecutive stages, that a residual 
dental lamina with thickened margin comes to project freely 
by the lingual side of the molars, just as in the case of the 
antemolar teeth. 
Concerning the Significance of Labial Outgrowths 
of the Lamina in the Molar Region. 
Holding such views as we do of the comparatively trifling 
significance to be attached to the occurrence of a residual 
dental lamina (even when “knob-like” or ‘ bud-like ” 
[“kolbig” or “knospenférmig™”] on cross-section), it be- 
comes the more important for us to come to a decision with 
regard to the real character of those labially directed out- 
growths of the dental lamina in the molar region noticed by 
Woodward. These, as has been mentioned above, have been 
interpreted by him as possible or even probable vestigial 
remains of predecessors of the existing molar teeth. 
In such vestiges he is inclined to believe (2, pp. 460 and 
470, and cf. 18, p. 630) we have the true serial homologues of 
the antemolar milk-teeth. 
It is plain that, from our point of view, a discovery of 
vestigial remains of teeth preceding the functional molars 
would tend to place the latter in the same category with, say, 
the permanent canine of Perameles, where, as has been 
shown, a pretty large residual dental lamina is differentiated 
alongside the Anlage of the permanent canine at a time when 
a mere vestige of the milk canine (dc.) alone remains (fig. 47). 
Woodward describes as “ present on the outer side of the 
enamel-organ (in Petrogale) a conspicuous outgrowth of 
its cells, extending down into the gum at right angles to the 
' Probably the future large size of the macropod molar has something to 
do with the relative delay in the process of its differentiation. 
