DEVELOPMENT AND SUCCESSION OF TEETH IN PERAMELES. 437 
stage in its tooth development the wombat possesses rudiments 
of teeth entirely unrepresented in the adult dentition; and 
that, further, certain of these teeth are precociously calcified, 
and, according to the author, obviously belong to a generation 
antecedent to that to which the permanent teeth of the animal 
belong. In addition to this he finds, in a position in the jaw 
corresponding to that occupied later by the single adult pre- 
molar, a single pointed, precociously calcified tooth, provided 
with a large and “ bulbous” lingual germ (“Ersatzleiste”), 
which latter he regards as the true germ of the permanent 
premolar; the rudimentary but well-formed calcified tooth 
beside it being the deciduous predecessor to which Owen 
apparently referred. 
In summing up his results Rose first emphasises the fact of 
the possession by the wombat of two typically distinct den- 
titions “ ganz iihnlich wie die placental en Sauger.”” Of these 
two incomplete series he points out that all the members of 
the first, and several of those of the second, must be resorbed 
in early life. 
He then proceeds to put the important question, ‘ which of 
the two tooth-series of wombat corresponds to the milk series 
of other Marsupials?”? And just here he finds himself in- 
volved in some little difficulty. For, while he finds it easy to 
homologise the posterior elements of the series with those 
found in other Marsupials by reckoning the “ Ersatzleiste” 
of the small calcified “‘ premolar” as the germ of the persist- 
ing one, he feels almost compelled to identify the calcified and 
precocious germs of the first generation in the anterior seg- 
ment of the jaw with the “milk” (persisting) dentition of 
other Marsupials. He is thus led to postulate a fundamental 
difference in homology between the teeth of the anterior and 
posterior segments of the jaw respectively, and thus also be- 
tween the anterior persisting teeth of wombat and those of 
other Marsupials. “ Wahrend die Schneidezahne der polypro- 
todont Beutler zur ersten oder Milchzahnserie gehoren, rechnen 
diejenigen vom Wombat zur zweiten oder bleibenden.” He 
adds, however, that it is not improbable that the condition 
