210 EDENTATA 
having a rudimentary crown, and a distinct anterior and posterior 
root. The other milk-teeth are styliform, the four anterior ones 
being very minute, and separated from one another by equal 
intervals; the foremost of all is situated immediately behind the 
premaxillo-maxillary suture. In the mandible only four milk-teeth 
have hitherto been detected, of which the hindmost has the 
comparatively complex form found in the corresponding upper tooth. 
None of these milk-teeth appear, however, to cut the gum, so that 
the whole set is entirely functionless. Under the microscope these 
milk-teeth show signs of possessing a commencement of the 
remarkable histological structure found in the permanent teeth. 
Mr. Thomas remarks that since “the three large posterior teeth 
of Orycteropus, already distinguished by their more molariform shape, 
do not have milk-predecessors, while all the small teeth anterior to 
them do, and in addition the last milk-tooth is markedly different 
from those in front of it, we ought apparently no longer to look 
upon this animal as an homodont, but instead to consider it as an 
originally heterodont form in which the incisors and canines have 
been suppressed to allow free play to the mobile vermiform tongue. 
“But important as a knowledge of the presence of a milk- 
dentition in Orycteropus is, it does not at present render any easier 
the difficult questions as to the phylogeny and systematic position 
of that animal. Although called an Edentate, it has always been 
recognised as possessing many characters exceedingly different from 
those of the typical American members of the order. It has in fact 
been placed with them rather on account of the inconvenience of 
forming a special order for its reception than because of its real 
relationship to them. Now, as they are either altogether toothless, 
or else homodont and monophyodont (apart from the remarkable 
exception of Tatusta), it seems more than ever incorrect to unite 
with them the solitary member of the Tubulidentata, toothed, 
heterodont, and diphyodont, and differing from them in addition by 
its placentation, the anatomy of its reproductive organs, the minute 
structure of its teeth, and the general characters of its skeleton. 
“But if Orycteropus is not genetically a near relation of the 
Edentates, we are wholly in the dark as to what other mammals it 
is allied to, and I think it would be premature to hazard a guess on 
the subject. Whether even it has any special connection with 
Manis is a point about which there is the greatest doubt, and unfor- 
tunately we are as yet absolutely without any paleontological 
knowledge of the extinct allies of either. Afacrotherium even, 
usually supposed from the structure of its phalangeal bones, to be 
related to Manis, has lately proved to have the teeth and vertebrx 
of a perissodactyle Ungulate, and one could not dare to suggest 
that anceStors of Aunis, or Orycteropus were to be sought in that 
direction. Lastly, as the numerous fossil American Edentates do 
