[Illustration: Fig. 149. Right femur, back view—½ natural size.] MEASUREMENTS Femur, least diam. of the shaft 58 mm. Femur, diameter across the condyles 148 mm. =Physornis= sp.? Two phalanges of a size too small to belong to the above species represent a second smaller bird of this type, about equal in size to _Phororhacus inflatus_. I give a figure of one toe but would wait for more typical material before establishing a species. [Illustration: Fig. 150. Proximal phalanx of Physornis sp?—natural size.] [Illustration: Fig. 151. Loxornis clivus, lower end of tibio-tarsus, after Ameghino—natural size.] =Loxornis= Ameghino Loxornis Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 595. Another group of bones, which we found with considerable frequency, have the same features as _Pelecyornis_ of the Santa Cruz. Ameghino has described but the lower end of a tibio-tarsus which can be associated with these bones and to it gave the name _Loxornis_. I can not find much variation from _Pelecyornis_ except that the coracoid is considerably shorter and wider, and there is a slight variation in the lower end of the tibio-tarsus. These then are the bases of the generic name. =Loxornis clivus= Ameghino L. clivus Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 595. Under this name Ameghino has described the lower end of a tibio-tarsus, a figure of which I reproduce here. This is of a size to complete the tibio-tarsus which we found, lacking the lower end, and agrees in size with the other bones which we found, so that I shall describe my material under this name. The species is in size comparable to _Pelecyornis tubulatus_ with which it agrees closely. [Illustration: Fig. 152. Humerus—½ natural size.] [Illustration: Fig. 153. Sternum, thin parts lacking—½ natural size.] [Illustration: Fig. 154. Coracoid—½ natural size.] We found the upper four-fifths of a tibio-tarsus, associated with part of the fibula, the sternum, the humerus, and the coracoid; a second specimen consisting of a complete tarso-metatarsus, and fragments of the pelvis, vertebrae and wing bones; a third specimen consisting of part of the tibio-tarsus, and various fragments; a fourth consisting of a femur, and lastly two toes; all evidently representing one species, which in most respects is almost identical with _Pelecyornis tubulatus_. These all came from the Chico del Chubut, west of Puerto Visser. The humerus has a large head but is considerably flattened at the proximal end. The internal side is deeply excavated, the shaft is slender and light as though the wing were quite reduced, though not so much as in _Pelecyornis_ and not nearly as much as in _Phororhacus_.