DEVELOPMENT AND SUCCESSION OF TEETH IN PERAMELES, 563 
swollen portion of the dental lamina.” He goes on to remark 
that “‘ we can only interpret these appearances on the grounds 
that the functional molars belong to the second or replacing 
dentition, and that this downgrowth on their outer sides repre- 
sents the rudimentary, or rather vestigial, milk or first 
dentition.” 
We can fully confirm the observations of Woodward in 
regard to the existence of such labial projections as he has 
thus described (and figured in his figs. 25, @ and 8, and 26). 
The like are constantly seen in Perameles in certain regions, 
and at first we were inclined to interpret them in the same 
manner as Woodward has done. 
We have, however, been led to entertain grave doubts as to 
whether such a construction can legitimately be placed upon 
the facts observed by Woodward and ourselves. In the first 
place it may be observed that the whole labial surface of the 
dental lamina often presents considerable irregularity as com- 
pared with the lingual surface, and the irregularities not 
infrequently constitute actual outgrowths or processes. This 
condition is specially noticeable in those parts of the lamina in 
front of or behind the enamel-organ of a molar tooth (cf. fig. 
30, “d”). And even opposite the tooth-germ cellular projec- 
tions may be observed upon the labial aspect of the “ neck ” 
of the dental lamina, proximal to the place of attachment of 
the enamel-organ, as in figs. 28 and 29 (“a”). This kind of 
process appears to consist of cellular material, originally form- 
ing part of the enamel-organ, which has been left attached to 
the main stem or “neck ” of the lamina during the process of 
constriction off by which the enamel-organ is liberated from 
the lamina; and it is very probably comparable to those 
villus-like projections which not infrequently occur upon 
the outer surface of the developing enamel-organ itself. Indi- 
cations are shown in fig. 29, “c,” and especially in fig. 28, “c,” 
of such villous irregularities over the general surface of the 
enamel-organ of m-t towards its hinder end. In some sections, 
several (as many as three) labial projections from the neck of 
the dental lamina of the character indicated in figs. 27, 28, and 
VOL. 39, PART 4,—NEW SER, QQ 
