DEVELOPMENT AND SUCCESSION OF TEETH IN PERAMELES. 577 
PART IV. 
ConcLupING REMARKS. 
Before concluding this discussion it may not be wholly out 
of place to ask the question whether our observations and the 
conclusions deducible therefrom can be made to throw any 
light upon the more general problem of the affinities of Mar- 
supials with other mammalian groups. 
Hasty generalisation is certainly to be deprecated, and it is 
only with the greatest diffidence that we even approach the 
discussion of such a weighty question with the equipment of 
our own partial and imperfect knowledge, more especially of 
the paleontological aspects of the problem. 
There are, however, one or two more or less obvious deduc- 
tions from the views which have been advocated in the fore- 
going pages, and partially summarised in the introductory 
section of the paper (p. 441). 
It is plain that, if our view of the “ milk” homology of the 
so-called “ prelacteal” teeth be admitted, we are bound to 
believe that the marsupial order as a whole—if not derived 
from truly Eutherian ancestors, as seems unlikely from the 
general type or organisation exemplified—is at least an off- 
shoot from a diphyodont stock common to both Metatheria 
and Eutheria. 
Following upon the publication of Kiikenthal’s and Rése’s 
researches upon marsupial teeth, Osborn (34, p. 204) has 
remarked that “the discovery of the complete double series 
seems to have removed the last straw from the theory of the 
marsupial “ancestry of the Placentals.’ And the adoption 
of the conclusions of the present paper in no whit weakens the 
general purport of this criticism, since it still leaves un- 
touched the important fact that one of the two typical mamma- 
lian dentitions has been lost during the evolution of the Mar- 
supialia. In respect of their tooth-equipment then, the 
Metatheria are degenerate mammals. 
With this view it is interesting to correlate such specula- 
