532 J. T, WILSON AND J. P. HILL. 
able antecedent to the first formation of a true successional 
tooth. But it is not equally permissible to assert, conversely, 
that wherever such a feature is perceptible there we must 
recognise the presence of a rudiment of an enamel-organ 
belonging to a definite tooth generation. The fact is that 
under nearly all the discussions touching the ‘‘ swollen ” resi- 
dual lamina or “Ersatzleiste”’ of Marsupials—not even 
excluding Leche’s more critical remarks—there appears to us 
to lurk an assumption which is traceable to the use of some- 
what ambiguous descriptive terms. Thus the term “ bud” 
(“ Knospe’’) seems to us wholly misleading as descriptive of 
the somewhat thickened downgrowth (our residual dental 
lamina) so frequently met with by the sides of the developing 
enamel-organs in the marsupial jaw. The word ‘ bud-like ” 
(““knospenférmig”) may indeed describe the outline ap- 
pearance of the lingually prolonged lamina as seen in a 
cross-section, but it is thoroughly inapplicable to the actual 
solid form which that downgrowth really possesses, 
We must therefore raise a most emphatic protest against 
the use of a phraseology such as that employed by Leche in 
the following sentence :—‘‘ Zuniachst ist zu betonen, dass bei 
den Beutelthieren die Schmelzkeime der zweiten Dentition 
sich meist langer als die Schmelzleiste erhalten, also ganz wie 
bei einer Anlage, aus der ein Zahn sich wirklich entwickelt : 
hatte die Zahnanlage jede Bedeutung eingebusst, so ist 
schwer einzusehen, wesshalb sie als knospenformiger Schmelz- 
keim sich langer als ihr Mutterboden, die Schmelzleiste erhalten 
sollte” (8, p. 105). Here the distinction assumed between 
‘“enamel-germs of the second dentition” and the ‘ dental 
lamina” is a most unjustifiable one. The idea that, during 
disintegration of the latter, we can distinguish “ bud-like 
enamel-germs ”’ which are preserved longer than “the parent 
structure—the dental lamina” is a wholly fanciful one, de- 
pendent upon the confusion of the outlines of cross-sections 
with those of solid extended structures. 
In his recent criticism of Leche’s general attitude towards 
the question of marsupial teeth (27) Kiikenthal employs the 
