The second, larger and stronger, genus of Asiatic anthropoid ape is the orang (_Satyrus_); he is now found only in the islands of Borneo and Sumatra. Selenka, who has published a very thorough _Study of the Development and Cranial Structure of the Anthropoid Apes_ (1899), distinguishes ten races of the orang, which may, however, also be regarded as “local varieties or species.” They fall into two sub-genera or genera: one group, _Dyssatyrus_ (orang-bentang, Fig. 205), is distinguished for the strength of its limbs, and the formation of very peculiar and salient cheek-pads in the elderly male; these are wanting in the other group, the ordinary orang-outang (_Eusatyrus_). Several species have lately been distinguished in the two genera of the black African anthropoid apes (chimpanzee and gorilla). In the genus _Anthropithecus_ (or _Anthropopithecus,_ formerly _Troglodytes_), the bald-headed chimpanzee, _A. calvus_ (Fig. 206), and the gorilla-like _A. mafuca_ differ very strikingly from the ordinary _Anthropithecus niger_ (Fig. 207), not only in the size and proportion of many parts of the body, but also in the peculiar shape of the head, especially the ears and lips, and in the hair and colour. The controversy that still continues as to whether these different forms of chimpanzee and orang are “merely local varieties” or “true species” is an idle one; as in all such disputes of classifiers there is an utter absence of clear ideas as to what a species really is. Fig.206. The bald-headed chimpanzee (Anthropithecus calvus). Female. Fig. 206—The bald-headed chimpanzee (_Anthropithecus calvus_). Female. This fresh species, described by Frank Beddard in 1897 as Troglodytes calvus, differs considerably from the ordinary _A. niger_ Fig. 207) in the structure of the head, the colouring, and the absence of hair in parts. Of the largest and most famous of all the anthropoid apes, the gorilla, Paschen has lately discovered a giant-form in the interior of the Cameroons, which seems to differ from the ordinary species (_Gorilla gina_ Fig. 208), not only by its unusual size and strength, but also by a special formation of the skull. This giant gorilla (_Gorilla gigas,_ Fig. 209) is six feet eight inches long; the span of its great arms is about nine feet; its powerful chest is twice as broad as that of a strong man. Fig.207. Female chimpanzee (Anthropithecus niger). Fig. 207—Female chimpanzee (_Anthropithecus niger_). (From _ Brehm._)