If we wish to arrive at a natural system, and consequently at the pedigree of the Primates, we must go a step further still, and entirely separate the Semi-apes, or Prosimiæ, (Huxley’s last three families), from Genuine Apes, or Simiæ (the first four families). For, as I have already shown in my General Morphology, and explained in the last chapter, the Semi-apes differ in many and important respects from Genuine Apes, and in their individual forms are more closely allied to the various other orders of Discoplacentalia. Hence the Semi-apes must probably be considered as the remnants of the common primary group, out of which the other orders of Discoplacentalia, and, it may be, all Deciduata, have developed as two diverging branches. (Gen. Morph. ii. pp. 148 and 153.) But man cannot be separated from the order of Genuine Apes, or Simiæ, as he is in every respect more closely allied to the higher Genuine Apes than the latter are to the lower Genuine Apes. _Genuine Apes_ (Simiæ) are universally divided into two perfectly natural groups, namely, the Apes of the New World, or American Apes, and the Apes of the Old World, which are indigenous to Asia and Africa, and which formerly also existed in Europe. These two classes differ principally in the formation of the nose, and they have been named accordingly. American Apes have flat noses, so that the nostrils are in front, not below; hence they are called _Flat Noses_ (Platyrrhini). On the other hand, the Apes of the Old World have a narrow cartilaginous bridge, and the nostrils turned downwards, as in man; they are, therefore, called _Narrow Noses_ (Catarrhini). Further, the jaw, which plays an important part in the classification of Mammals, is essentially distinct in these two groups. All Catarrhinæ, or Apes of the Old World, have exactly the same jaws as Man, namely, in each jaw four incisors above and below, then on each side a canine tooth and five cheek teeth, of which two are pre-molars and three molars, altogether thirty-two teeth. But all Apes of the New World, all Platyrrhini, have four more cheek teeth, namely, three pre-molars and three molars on each side, above and below: they consequently possess thirty-six teeth. Only one small group forms an exception to this rule, namely, the _Arctopitheci_, or _Clawed Apes_, in whom the third molar has degenerated, and they accordingly have on each half of their jaw three pre-molars and two molars. They also differ from the other Platyrrhini by having claws on the fingers of their hands and the toes of their feet, not nails like Man and the other Apes. This small group of South American Apes, which includes among others the well-known pretty little Midas-monkey and the Jacchus, must probably be considered only as a peculiarly developed lateral branch of the Platyrrhini.