1882. ] PROF. W. H. FLOWER ON THE EDENTATA. 365 
by the disappearance of the foetal villi at the two poles of the ovum ; 
while the small size of the umbilical vesicle indicates that it is not, 
like the zonary placenta of the Carnivora, directly derived from 
a type with both allantoic and umbilical vascularization of the 
chorion. 
Although paleontology has revealed the existence of a vast 
number of the Edentates by which the New World was tenanted in 
the Pleistocene age, and has given us a more perfect idea of their 
characters than is known of most other extinct forms, unfortu- 
nately the history of the group throughout the period of the true 
Tertiaries is at present almost a blank. The presence of a large 
species probably allied to Manis in the Siwalik fauna is indicated by 
a single phalanx, described and figured by Lydekker under the name 
of M. sindiensis. No animals, attributed with any certainty to the 
Edentata, are known of Eocene age. The few scattered and imperfect 
remains of supposed Edentates, Macrotherium and Ancylotherium, 
of the European later Miocene formations, and the similarly imperfect 
and as yet not fully described bones of Moropus and Morotherium of 
corresponding ages in North America, indicate that animals existed 
at that time of large size, presenting characters in some respects 
allied to the recent members of the order, but in others so different 
that they cannot be placed in any of the existing families. Macro- 
therium, for instance, appears to have limb-characters which ally it 
to the Ungulates. As far as can be surmised at present, the 
affinities of these early forms were rather with the existing members 
which survive in their own part of the world, than with those of a 
different hemisphere. Macrotherium certainly appears to present 
more resemblance to Manis than to the American Edentates. The first 
fragments of it which were found were attributed by Cuvier to a 
“* Pangolin gigantesque.” But some evidence has since been found 
in favour of its having possessed teeth. So far this is quite what 
might be expected; but it certainly throws very little light either 
upon the mutual relations of the existing forms, the steps by which the 
present state of things has been brought about, or, what would be still 
more interesting, their affinities with mammals of other groups. The 
tabular form (see p. 366) into which the result of these inquiries have 
been thrown will show what I conceive to be the relationship of the 
existing forms ; but it also shows the great deficiency of our knowledge 
of the group in past ages. 
The general conclusions to which a study of this group have led me 
may be summed up as follows:—All the American Edentates at 
present known, however diversified in form and habits, belong to a 
common stock. The Bradypodide, Megatheriide, and Myrmeco- 
phagide are closely allied, the modifications seen in the existing 
families relating to food and manner of life. The ancestral forms 
may have been omnivorous, like the present Armadillos, and 
gradually separated into the purely vegetable and purely animal 
feeders ; from the former are developed the modern Sloths, from the 
latter the Anteaters. The Armadillos are another modification of 
the same type, retaining some more generalized characters, as those 
