DEVELOPMENT AND SUCCESSION OF TEETH IN PERAMELES. 505 
The thickening of the residual lamina becomes even more 
sharply accentuated than in fig. 63 in sections further back. 
The deciduous premolar is a well-calcified tooth having a 
sharply pointed chief cusp, while the anterior portion through 
which the section passes in fig. 63 shows a low and flattened 
crown. 
Behind dp® the continued dental lamina becomes more uni- 
form in thickness. In the region of m+ traces of the connec- 
tion with the latter tooth are discernible, as also in region of 
m2, <A residual lamina is present in both regions. 
Towards the end of the region of the second molar the well- 
marked dental lamina becomes gradually more highly de- 
veloped, still retaining a well-marked laminar projection 
towards m2—the remains of its original connection with the 
dental lamina (fig. 68, cb, m2). Then, somewhat abruptly, the 
residual lamina beyond (distal to) the ‘ Verbindungs- 
briicke’ develops a marked labial bulging, so that it appears 
as a knobbed swelling, flattened or even slightly concave dis- 
tally, forming the Anlage of m3 (fig. 684). The connective 
tissue exhibits a very evident condensation and cellular ac- 
cumulation where it is in relation with the flattened or slightly 
concave surface—the rudiment of the papilla of m3. 
Lower Jaw.—The undifferentiated segment of dental 
lamina in front of the first incisor is again in evidence, and its 
swelling is now more marked than in the preceding stage, 
though, as in the latter, it tapers away and becomes more 
flattened and attenuated before being continued into the 
residual dental lamina beside 77. This residual lamina is now 
greatly reduced in thickness, and no longer exhibits traces of 
its former connection with 7. 
Beyond the progressive enlargement and perfecting of the 
three incisors there is little further to note. The vestigial 
diz is still present as a strongly calcified toothlet on the labial 
side of 7; near the oral surface. Its outer dentine layer appa- 
rently forms now a complete shell surrounded by a layer of 
deeply staining cells. The central nuclei appear altered and 
degenerated. 
