The name given by the Dyaks to the larger species is "Mias Pappan." There is, however, a smaller variety, which they designate "Mias Kassu," of which Dr. Wallace has given an excellent and detailed account. These Mias Kassu have no tumour-like expansions on the sides of the head; the median crest is {180}absent from the skull, for the muscular ridges remain some distance apart; the teeth are very large, especially the canines and the middle upper incisors. The females, which are smaller than the males, are also without the cheek-swellings and the prominent crests of the male, and have smaller canine teeth. This variety, named _Simia morio_ by Sir R. Owen, bears a close similarity to that found in Sumatra. It has been considered a distinct species both by Owen and Wallace, but the variation, as the latter naturalist himself admits, is so very great in just those characters which have been considered to separate "Mias Kassu" from "Mias Pappan," that it is highly probable that both are of the same species, but of different ages. Mr. Beddard found that an Ape exhibited in the Zoological Gardens as an adult example of _S. morio_ was in reality immature. THE GORILLAS. GENUS GORILLA. _Troglodytes_, Geoffr., Ann. Mus., xix., p. 87 (1812). _Gorilla_, Is. Geoffr., C. R., xxxiv., p. 84, note (1852). This genus, like the preceding, contains but a single species, THE GORILLA. GORILLA GORILLA. _Troglodytes gorilla_, Wyman, Bost. Journ. Nat. Hist. (2), v., p. 419, pls. 1-4 (1847); Winwood-Reade, P. Z. S., 1863, p. 171; Owen, Tr. Z. S., ii., p. 381; v., pp. 1, 243, pls. i.-xiii., and xliii.-xlix; Scl., P. Z. S., 1877, p. 303; Cunningham, Mem. Roy. Irish Ac., p. 1 (1886). _Gorilla gina_, Is. Geoffr., Arch. Mus., viii., pls. 2-4 (1852). _Troglodytes savagei_, Owen, P. Z. S., 1848, p. 29. _Gorilla savagei_, Is. Geoffr., Rev. et. Mag. de Zool., p. 104 (1853); Gray, Cat. Monkeys Brit. Mus., p. 7 (1870). _Pithecus gorilla_, Blainv., Osteogr., pls. 2, et 5 bis (errore _P. gesilla_). PLATE XL. [Illustration: THE GORILLA.] {181} _Satyrus adrotes_, Meyer, Arch. f. Naturg., p. 182 (1856). _Simia gorilla_, Schl., Mus. Pays-Bas, vii., p. 8 (1876). _Gorilla mayema_, Alix et Bouv. C. R., lxxxv., p. 58 (1878). (_Plate XL._) CHARACTERS.--The face of this massive and most ponderous of all the Apes is naked and black, very wide and elongated. The large head has a ridge of hair along the central crest, and its lower jaw is very wide and far extended backward. The nose is long and high, and broad and flat at its extremity, and is also grooved longitudinally. The muzzle is broad, the mouth wide; the upper lip short, and the lower mobile and protrudable. The eyes are large; the ears naked and black, with the posterior upper angle pointed, and the lower margin produced into a rudimentary pendulous lobule.