230 THE DESEADO FORMATION OF PATAGONIA 



The humerus has a large head but is considerably flat- 

 tened 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. 



The sternum had a moderate keel but both this and body 

 of the bone are very thin, so much so, that in my specimen, 

 much is broken away, giving the figure the appearance of 

 the bone being fenestrated, which was not the case. In 

 general the sternum is similar to Pelecyornis. 



The coracoid is a decidedly stout bone, with a' wide dis- 

 tal end for articulation of the sternum. The proximal end 

 has a long articular facet for the scapula. This bone is 

 heavier than the corresponding one in Pelecyornis. 



The femur has a small rounded head on a short neck, 

 the articular surface spreading over the entire proximal 

 end of the bone. Thus the trochanter is abbreviated and 

 does not rise above the top of the head. The shaft is of 

 considerable length and fairly heavy. 



The tibio-tarsus has a wide flaring end to receive the 

 articulation of the femur. The bone is very long as in 

 Pelecyornis. On the external side is a long ridge along 

 which the fibula was attached by cartilage or by ligaments, 

 but was not fused to the tibio-tarsus. The shaft is approxi- 

 mately cylindrical in section and fairly heavy. The distal 

 end is missing, but if I have associated correctly the speci- 

 men figured by Ameghino, the condyles are flattened, the 

 inner being the flatter, and the outer rising in a narrow 

 margin. 



Figure 157 shows a fibula which would have occupied the 

 position indicated along the side of the tibio-tarsus and 

 corresponds entirely with the same bone in Pelecyornis. 



The tarso-metatarsus is long and slender, almost exactly 

 the counterpart of the same bone in Pelecyornis. The bone 

 has a triangular upper end, with two shallow articular 



