The reproductive organs and placentation of _Orycteropus_ are formed upon a principle unknown in the more typical Edentates, or, in combination, in any other mammals. Thus the testes, in the one described example, were inguinal, but appeared to descend, at all events temporarily, into a scrotum; but the penis is scarcely larger than that of the Great Anteater. The uterus is still more fully bicornuate than in _Manis_, with its two lateral chambers opening separately into the vagina, as in certain Rodents. The placenta is broadly zonary, but it is not known whether it is deciduate or not. It might readily be derived from the diffused placenta of _Manis_ by the abortion of the fœtal villi at the two poles of the ovum. The _Orycteropodidæ_ have long been regarded as widely different from other Edentates, their presumed affinity with the _Manidæ_ being more or less problematical; but the discovery recently made by Mr. O. Thomas[115] that they have a milk-dentition still further emphasises their aberrant nature. According to this observer, it appears that there are normally no less than seven milk-teeth in the upper jaw, the hindmost of which is far larger than the others, 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.