separated branches of dogs and sea dogs. In both cases the complete transformation of the external form, consequent upon adaptation to entirely different conditions of life, has not been able to efface the solid foundation of the inherited internal peculiarities. According to Huxley’s opinion, which has already been quoted, only the Herbivorous Whales (Sirenia) are derived from Hoofed animals; on the other hand, the Carnivorous Cetacea (Sarcoceta) are derived from the marine animals of prey; the Zeuglodonts would form a transition between the two latter. But in this case it would be difficult to understand the close anatomical relations which exist between the Herbivorous and Carnivorous Cetacea. The strange peculiarities in the internal and external structure which so strikingly distinguish the two groups from all other mammals would then have to be regarded only as _analogies_ (caused by the same kinds of adaptation), not as _homologies_ (transmitted from a common primary form). The latter, however, strikes me as being by far the more probable, and hence I have left all the Cetacea among the Indeciduata as one group of kindred origin. The remarkable order of _Flying Mammals_, or _Bats_ (Chiroptera), stands near to the Carnaria as well as to the Insectivora. It has become strikingly transformed by adaptation to a flying mode of life, just as marine animals of prey have become modified by adaptation to a swimming mode of life. This order probably also originated out of the Semi-apes, with which it is even at present closely allied, through the flying lemurs (Galeopithecus). Of the two orders of flying animals, the insect-eating forms, or _flying mice_ (Nycterides), probably developed out of those eating fruits, or _flying foxes_ (Pterocynes); for the latter are, in many ways, more closely allied to Semi-apes than are the former. We have now still to discuss the genuine Apes (Simiæ) as the last order of Mammals; but as, according to the zoological system, the human race belongs to this order, and as it undoubtedly developed historically out of a branch of this order, we shall devote a special chapter to a more careful examination of its pedigree and history. CHAPTER XXII. ORIGIN AND PEDIGREE OF MAN.