This genus is founded on a very large leg-bone from the Pleistocene bone-caves of Brazil. The species has been described as PROTOPITHECUS BRASILIENSIS, Lund. GENUS CALLITHRIX (Vol. I., p. 158). Two species have been described from the Pleistocene bone-caves of Brazil: CALLITHRIX CHLOROCNOMYS, Lund, and C. PRIMÆVA, Lund (= _C. antiqua_, Lund). GENUS ALOUATTA (Vol. I., p. 192). Remains of one species, ALOUATTA URSINA (p. 149), has been discovered in the Pleistocene bone-caves of Brazil. GENUS CEBUS (Vol. I., p. 204). The Pleistocene bone-caverns of Brazil have preserved three species: one extinct, CEBUS MACROGNATHUS, Lund, and two still living, C. FATUELLUS, Linn., and C. CIRRIFER, Geoffr. {211}GENUS HOMUNCULUS. _Homunculus_, Ameghino, Rev. Argent. Hist. Nat., i., pp. 290, 384 (1891). _Ecphantodon_, Mercenat, Rev. Mus. La Plata, ii., p. 74, pl. ii.; Zittel, Handb. Palæont., iv., p. 704 (1893). The dental formula of this genus is I2/2, C1/1, P3/3, M3/3. The diastema, or break, in the dental series is very small; the incisors are chisel-shaped, the outer pair smaller than the inner pair. The canines, which have a small basal cusp behind, are only slightly prominent; the pre-molars have one root, and one low outer cusp, and two higher inner cusps. The molars are quadrangular, with two pairs of cusps, each united obliquely by a ridge; the anterior molar is smaller than the two hinder. The arm-bone (_humerus_) has an ent-epi-condylar foramen. (_Zittel._) The front surface of the line of union of the two halves of the lower jaw is vertical. The terminal joints of the digits have nails. The thumb and the great-toe are opposable. HOMUNCULUS PATAGONICUS, Ameghino (= _Ecphantodon ceboides_, Mercenat), the only known species, is found in the Upper Eocene or Oligocene of Santa Cruz, Patagonia. GENUS ANTHROPOPS. _Anthropops_, Ameghino, Rev. Arg. Nat. Hist., i., p. 387 (1891); Zittel, Handb. Palæont., iv., p. 704 (1893). This genus is known from only a fragment of a lower jaw containing four small incisors, two strong canines, and anterior and median pre-molars, both one-rooted. One species, ANTHROPOPS PERFECTUS, Ameghino, from the older Tertiary (Upper Eocene or Oligocene) beds of Santa Cruz, Patagonia, is known. Two genera, _Homocentrus_ (H. ARGENTINUS, Amegh.) and {212}_Eudiastus_ (E. LINGULATUS, Amegh.), described by Ameghino, from the Santa Cruz beds in Patagonia, are not yet sufficiently characterised. FAMILY CERCOPITHECIDÆ (Vol. I., p. 248). GENUS PAPIO (_suprà_, p. 253). Several species of this still living genus have been recovered from strata of the Tertiary epoch: PAPIO SUB-HIMALAYANUS (Meyer), from the Sivalik hills, of Lower Pliocene age; P. FALCONERI (Lydekker), from the Pleistocene bone-caves of Madras, India, and in the superficial deposits of Algeria, North Africa; and P. ATLANTICUS (Thomas). The Sivalik species was closely related to the existing North-African Baboons. GENUS OREOPITHECUS.