DEVELOPMENT AND SUCCESSION OF TEETH IN PERAMELES. 491 
In his paper already referred to Mr. Woodward makes the 
following statement:—“It is interesting to note that in 
Perameles the large supposed successional tooth is quite 
distinct in origin from the small fourth premolar which is shed 
[dp.*]|; it is, in fact, formed from the dental lamina situated 
immediately behind pm 3 [p2] and morphologically in front 
of the fourth premolar [ p2]” (2, p. 467). It is unfortunate 
that Mr. Woodward makes this statement without amplifying 
it by a more detailed description or illustrating it by drawings 
(for Perameles). 
From our own minute and detailed study in Perameles of 
the region of the dental lamina concerned we are convinced 
that Mr. Woodward has misinterpreted the appearances there 
met with. We do not deny that the latter may sometimes 
seem to suggest the view that Woodward adopts, but upon 
further examination it becomes untenable. In the absence of 
any figures the readers of Woodward’s description would 
necessarily suppose that in Perameles one meets with just 
such an enlargement of the dental lamina between p2 and 
dp2 (his “pm. 3” and “dpm 4”’) as is represented in the wax 
model of the corresponding region of Petrogale figured by 
him. But this is by no means the case. In connection with 
the description of Stage 111 of Perameles we have drawn 
attention to the fact that the dental lamina behind p2 gradu- 
ally tapers backwards from the thickening which represents 
the enamel-organ of the latter tooth, and that, as it approaches 
the region of dp3, it becomes somewhat more slender, but at 
the same time distinctly more elongated vertically. (See text, 
Fig. 1, a—c.) There is no localised enlargement whatever of 
the stretch of lamina between p2 and dp3. It is true that it 
is plump and well developed, but this does not specially distin- 
guish it at the stage in question from stretches of the lamina 
between other tooth Anlagen. 
We have already pointed out that in fig. 22 the apparent 
swelling of the dental lamina in front of the region of dp2 is 
due merely to its plane of section. To understand it properly 
the gradual vertical elongation of the lamina behind p2 must 
