We thus find, both in the Mammalia and birds of West Africa, a special Oriental or even Malayan element not present in the other parts of tropical Africa, although appearing again in Madagascar. In the Mammalia it is represented by the anthropoid apes; by _Colobus_ allied to _Semnopithecus_, and by _Cercocebus_ allied to _Macacus_; and especially by a form of the Malayan family of chevrotains (Tragulidæ). The Malayan genus of otters, _Aonyx_, is also said to occur in West and South Africa. In birds we have special Oriental and Malayan affinities in _Alethe_, _Pholidornis_, _Berenicornis_, _Pitta_, and _Palæornis;_ while the Oriental genus _Treron_ has a wide range in Africa. We shall {264}endeavour to ascertain the meaning of this special relation at a subsequent stage of our inquiries. _Plate V._--_River Scene in West Africa, with Characteristic Animals._--Our artist has here well represented the luxuriance and beauty of a tropical forest; and the whole scene is such as might be witnessed on the banks of one of the rivers of equatorial West Africa. On the right we see a red river-hog (_Potamochoerus penicillatus_), one of the handsomest of the swine family, and highly characteristic of the West African sub-region. In a tree overhead is the potto (_Perodicticus potto_), one of the curious forms of lemur confined to West Africa. On the left is the remarkable _Potamogale velox_, first discovered by Du Chaillu,--an Insectivorous animal, with the form and habits of an otter. On the other side of the river are seen a pair of gorillas (_Troglodytes gorilla_), the largest of the anthropoid apes. The bird on the wing is the Whydah finch (_Vidua paradisea_), remarkable for the enormous plumes with which the tail of the male bird is decorated during the breeding season. The crested bird overhead is one of the beautiful green touracos (_Turacus macrorhynchus_), belonging to the Musophagidæ, or plantain-eaters, a family wholly African, and most abundant in the western sub-region. _Reptiles._--In this class we find a large number of peculiar forms; 13 genera of snakes, 3 of lizards, and 2 of tortoises being confined to the sub-region. The snakes are _Pariaspis_, _Elapops_, and _Prosymna_ (Calamariidæ), _Rhamnophis_, _Herpetethiops_, and _Grayia_ (Colubridæ), _Neusterophis_ and _Limnophis_ (Homalopsidæ), _Simocephalus_ and _Holurophis_ (Lycodontidæ); _Pelophilus_ (Pythonidæ); _Elapsoidea_ (Elapidæ); and _Atheris_ (Viperidæ). The lizards are _Dalophia_ (Lepidosternidæ); _Otosaurus_ (Scincidæ); _Psilodactylus_ (Geckotidæ). The tortoises, _Cinyxis_ (Testudinidæ) and _Tetrathyra_ (Trionichidæ). _Amphibia._--Of Amphibia, there are 2 peculiar genera of tree-frogs, _Hylambatis_ and _Hemimantis_, belonging to the Polypedatidæ. Plate V. [Illustration] SCENE IN WEST AFRICA, WITH CHARACTERISTIC ANIMALS.