226 THE DESEADO FORMATION OF PATAGONIA 



had a head nearly twice as long and limb bones half again 

 as large as this species; so that it represented a bird nine 

 to ten feet high. Previously but one specimen of this type, 

 a part of a mandible, has been found in the Deseado beds. 

 We were fortunate enough to find the greater part of a 

 femur, indicating a bird equal to the largest of those in the 

 Santa Cruz. There are also toe bones of Phororachus of 

 a size about the same as P. inflatus. 



A host of names, generic and specific, have been given to 

 the individual bones of the birds of this type, but Ameghino, 

 in studying the birds of the Santa Cruz, brought them 

 all together under the single genus Phororhacus. (See Bol. 

 Inst. Geog. Argen., 1895, t. 15.) Referring to the single 

 bone in the Deseado, however, he gave it a new generic 

 name Physornis, which differs from Phororhacus only in 

 the lower jaw being more convex, but should stand until 

 better material has been found to establish whether it 

 differs enough to be entitled to generic independence. 



Physornis fortis Ameghino. 



P. fortis Amegh., 1895, Bol. Inst. Geog. Argen., t. 15, p. 576. 



Under this specific name Ameghino describes a part of the 

 lower jaw 150 mm. long which he says equals in size Phoror- 

 hacus longissimus, and differs only in the greater convexity 

 of the mandible. Our specimen is a femur, apparently of 

 the same bird, being of the type of Phororhacus and about 

 the size of P. longissimus; so I have placed it in this species. 



This femur is of large size, moderate length, and has a 

 shaft subcylindrical in section. The distal end is expanded 

 and the condyles are flattened, the inner one being the wider, 

 the outer condylc being narrower and the external margin 

 projecting to make a high ridge. The pit on the posterior 

 side of the shaft just above the condyles is unusually deep 

 and of large size. On the anterior side there extends from 

 either condyle a low marginal ridge which soon fades into 



