DEVELOPMENT AND SUCCESSION OF TEETH IN PERAMELES. 565 
and persistent continuity in the hindmost molar region forbid 
our regarding it as a more or less accidental or capriciously 
developed villous outgrowth or process. But at the same time 
the fact that it does not constitute any mere knob-like excres- 
cence, but that it really extends longitudinally back- 
wards asa flattened laminar or ridge-like outgrowth, 
seemed to us upon closer consideration to be unfavorable to 
its claims to be regarded as of rudimentary or vestigial dental 
character. 
On examining the next succeeding stage (1v), where m2 is 
a well-developed enamel-organ, and m3 has attained a degree 
of development comparable to that of m2 in Stage 111, we 
find that the secondary labial ridge or lamina aforesaid has 
now disappeared opposite m+ and up to near the hinder part 
of the now developed m2. Its disappearance is associated 
with the disappearance in most of the sections of the connec- 
tion between the dental lamina and the oral epithelium, i.e. 
with the onset of disintegration of the proximal portion of the 
dental lamina. 
But towards the hinder end of the now well-developed m2 
the secondary labial laminar outgrowth again comes into view 
(figs. 52 and 53, /.0.), this time extending backwards from 
near the hinder end of m2 to the posterior limit of the dental 
lamina with its thickened Anlage of m3 (fig. 54, /.0.). 
We see, therefore, that the conditions which formerly 
obtained further forwards are exactly repeated here at the pro- 
gressively growing segment of the dental lamina. Here 
again, however, there is nothing to suggest a vestigial dental 
character. The continuous laminar character, indeed, is an 
indication to the contrary. 
We may sum up these and further observations in this 
direction by affirming that, towards the hinder end of the 
dental lamina (which in the molar region is the growing end, 
and is thus ontogenetically younger than the parts of the 
lamina in front of it), there is constantly to be found, in addi- 
tion to the main stem or axis, as it were, of the dental lamina 
a secondary offshoot or lateral leaf-like outgrowth, directed 
