1912] Miller: Pacific Coast Avian Palaeontology 



93 



Haliaetus leucocephalus, and Geranoaetus melanoleucus. Aquila 

 pliogryps Shufeldt is described from a single bone, the basal 

 phalanx of the right hallux. The species is considered to be 

 slightly larger but more slender-limbed than Aquila chrysaetos. 

 The material representing the species is so limited that no clear 

 impression of its closer relationships can be formed. Morph- 

 nus wooclicarcli from Rancho La Brea may well have been such 

 a bird, though there is no way of obtaining more than the sug- 

 gestion of similarity from the fact that they were both eagles 

 of slender build. The statement made by Shufeldt is that Aquila 

 pliogryps was slender of foot, as indicated by the slightly longer 

 digits. Morphnus is a genus of long-shanked eagles with rela- 

 tively weak feet, as indicated by the size of the trochleae. The 

 digits certainly must have been much smaller in Morphnus wood- 

 war di than in Aquila chrysaetos or in A. pliogryps. 



Shufeldt 's species, A. sodalis, is founded on the proximal 

 part of a tarsometatarsus. The specimen is figured from the 

 anterior aspect drawn to natural scale. Compared with the 

 Rancho La Brea eagles, A. sodalis corresponds quite closely in 

 size with Geranoaetus fragilis, the smallest of the group there 

 represented. A. sodalis seems, however, to be of an entirely dif- 

 ferent nature if the position of the papilla of the tibialis anticus 

 may be taken as indicative. In a discussion of the splendid 

 series of eagle tarsi from the asphalt, it has been pointed out 

 by the author 27 that the position of this tubercle seemed to bear 

 a very definite relation to the slenderness of the tarsus, i.e., the 

 long-shanked forms have the tubercle placed high up on the 

 shaft of the bone. Applying this principle to Shufeldt 's figiire 

 of A. sodalis, it would seem that the Fossil Lake species was 

 not of the same group of eagles as the more southern genera 

 Morphnus and Geranoaetus assembled by Ridgway under the 

 caption Morphni. In A. sodalis the papilla of the tibialis anticus 

 is placed farther down the shaft and the proximal foramina are 

 separated by a much wider space. Unfortunately the charac- 

 ter of the hypotarsus is not shown in Shufeldt 's figure of Aquila 

 sodalis nor is an accurate impression of the region obtainable 

 from the description. It seems proper to consider the two species 



87 Miller, L. H., Univ. Calif. Pub!., Bull. Dept. Geol., vol. 6, p. 305, 1911. 



