MEASUREMENTS, SPECIMEN NO. 3287 NO. 3275 Femur, length 289 mm. diameter across gr. trochanter 80 mm. diameter of middle of shaft 32 mm. diameter of distal end 70 mm. Tibia, diameter of shaft 28 mm., 24 mm. diameter at distal end 38 mm., 36 mm. Calcaneum, length 103 mm., 96 mm. width 36 mm., 35 mm. Astragulus, length 48 mm., 44 mm. width 38 mm., 35 mm. Metatarsus II, length 114 mm., 105 mm. Metatarsus III, length 122 mm., 114 mm. Metatarsus IV, length 110 mm., 101 mm. Phalanx 1 of digit III, length 49 mm. Phalanx 2 of digit III, length 27 mm. Phalanx 3 of digit III, length 29 mm. =Deuterotherium= Ameghino Deuterotherium Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 633. Deuterotherium Amegh., 1897, Bol. Inst. Geog. Argen., t. 18, p. 452. This genus was first founded on a clacaneum and a bit of the mandibular symphysis, to which were added, later, both the upper and lower premolar and molar teeth. As far as it is known, it is distinguished by the upper molars lacking the metaconule entirely, and being approximately like those of Thaotherium. The dental formula is given by Ameghino as 1 0 4 3 -------, 2 0 4 3 the same as Thaotherium. But one species has been described. =Deuterotherium distichum= Ameghino We did not find this species, but the teeth assigned to it are very characteristic, and so I reproduce Ameghino’s figure of them. The species is distinguished by its size primarily. The following are the chief measurements given. [Illustration: Fig. 13. Upper pm. 3-m. 3 of the left side—natural size, after Ameghino.] Upper dentition, pm. 3 to m. 3, length 50 mm. Lower dentition, inc. 1 to m. 3, length 80 mm. Macrauchenidae (= Mesorhinidae Amegh.)