496 Je Lf. WILSON AND J; PP: “HU: 
that any such “ secondary attachment” has been entered upon 
as Woodward has imagined to take place in his parallel case. 
We are perfectly confident that our interpretation is the 
correct one for Perameles. 
From the description of dp2 given above, it will be observed 
that it is still in a more advanced phase of evolution than 
the two anterior premolars. But the difference is rapidly 
becoming less marked. The comparatively rudimentary 
character of the deciduous premolar of Perameles is now 
expressing itself in a much less rapid increase in size, so that 
it is now being rapidly overhauled in its progress by the 
enamel-organs of p+ and p2. In consequence of this fact, the 
very striking discrepancy in the periods of appearance of the 
enamel-organs of dp> and of the anterior premolars respectively, 
is, from now on, less and less apparent. It is thus quite 
easy to understand how observations upon a series of stages 
which did not include any younger than the present (Stage rv) 
might lead to the conclusion that these teeth were serially 
homologous. 
The appearance of the upper first molar in Stage tv is 
represented in fig. 51. Here, as in dp3, a thin dentine cap is 
present over the summit of the protocone. A well-marked 
residual dental lamina (rdl.) is present, whose significance will 
be discussed in connection with the general question of molar 
homology. ‘This figure alone is sufficient to disprove Wood- 
ward’s view (2) that “lingual downgrowths of the dental 
lamina” do not occur in connection with the molar teeth. 
Two drawings (figs. 52 and 53) are given of the enamel- 
organ of m2 from distinct series of sections (and not quite at 
corresponding points). In each case a well-marked swollen 
(“knospenférmig ”) “Ersatzleiste” or residual dental 
lamina (rdJ.) is visible. 
There is also a small labial “ sprout ” or “ outgrowth ” (/.0.) 
opposite a knee-like bend or “ Knickung” of the lamina, the 
significance of which is elsewhere discussed. 
1 Woodward has apparently given up this view, so far at least as certain 
rodents are concerned (cf. 18). 
