DEVELOPMENT AND SUCCESSION OF TEETH IN PERAMELES. 433 
Marsupials was a primitive condition, and that the original 
mammalian stock was actually monophyodont, had not met 
with general acceptance previous to the publication of Thomas’s 
paper in 1887. Notably Winge (6)! maintained, as against 
Flower, that in all probability the condition in Marsupials was 
secondary, and due to an almost complete loss of the milk 
dentition in that group; and this opinion of Winge possessed 
many adherents. 
The emphatic reiteration of the views of Flower by so emi- 
nent an investigator as Oldfield Thomas, upon the grounds of 
his own extensive researches, seems to have served as a stimulus 
to renewed consideration of the subject of marsupial dentition, 
especially from the developmental point of view. The first- 
fruits of the latter research appeared in December, 1891, in 
the form of a paper by Kiukenthal (7) on tooth development 
in Didelphys. 
In his introductory remarks Kikenthal indicates the Flower- 
Thomas theory of the primitive character of the single tooth- 
change in Marsupials as the prime consideration with refer- 
ence to which his investigations were directed. Thomas had 
admitted that a discovery of successional germs accessory to the 
non-changing marsupial (antemolar) teeth would be fatal to 
the theory in question, and the result of Kiikenthal’s exami- 
nation of Didelphys was to reveal the presence, at the lingual 
sides of nearly all the developing teeth in that animal, of 
epithelial ingrowths of the primitive dental lamina. These 
ingrowths he naturally interpreted as rudimentary enamel- 
germs of successional teeth, in series with the undoubted 
enamel-germ of the actual successional premolar (p 3, i.e. 
pm. 4 of Thomas). 
Kukenthal thus believed that he had established on a per- 
fectly secure basis, the view that the existing teeth of Marsu- 
pials in front of the last premolar are in reality milk-teeth in 
series, not with the persisting last premolar, but with its milk 
1 We have been unable to consult Winge’s original paper, and have had to 
rely for our knowledge of his views upon the accounts of Kiikenthal and 
Leche. 
