94 University of California Publications in Geology [V 0L - 7 



described by Shufeldt as distinct from any of the Rancho La 

 Brea forms. 



Aquila dananus Marsh 28 is described as being slightly smaller 

 than the existing A. chrysa'etos. A single specimen of the species 

 was taken in the Loup Fork of Nebraska. It consists of the 

 distal part of the tibia only and is not figured by Marsh in the 

 original description. The assignment of the specimen to the 

 genus Aquila is proper in the absence of any feature to dis- 

 tinguish it from that genus. The suggestion of the possible 

 identity of one of the Fossil Lake forms, A. social is, with Marsh's 

 A. dananus is made in Shufeldt 's paper but that author con- 

 siders the case improbable on the score of smaller dimensions in 

 the former species. Geranoa'etus gracilis Miller from the asphalt 

 is the smallest of the fossil eagles from California and, as indi- 

 cated above, this species is about the same size as A. sodalis Shu- 

 feldt. Marsh himself considered the Loup Fork specimen to be 

 "nearly as large as the Golden Eagle," in which case A. dananus 

 may be considered as probably intermediate in size between 

 Aquila chrysa'etos (Linnaeus) and Morphnus woodwardi Miller. 



The only other fossil falconids from American localities out- 

 side of California are Cope's Palaeoborus umbrosus, 29 which 

 Lucas 30 very properly ascribes to the Polyborinae, and two species 

 from South America recorded by the Argentine palaeontologists, 

 Moreno and Mercerat. 31 Lagopterus minutus Mor. and Mer. is 

 the smaller of these two South American species. It is repre- 

 sented by an almost perfect humerus which, according to the 

 authors describing it. is intermediate between Buteo and Poly- 

 borus, with the preponderance of characters relating it with 

 Polyborus. The other species, Foetopterus ambiguus, Mor. and 

 Mer.. is considered to be intermediate between Buteo and Cath- 

 artes, but is assigned by the authors to the Falconidae. The 



28 Marsh, O. C, Am. Journ. Sci., vol. 2, p. 125, Aug. 1871. 

 -s Cope, E. D., U. S. Geol. Surv. W. of 100th MericL, vol. 4, pt. 2, p. 287, 

 187(3. 



so Zittel, Textbook of Palaeontology, trans, by Eastman, vol. 2, p. 277, 

 1902. 



si Moreno and Mercerat, Palae. Argentina, An. Mus. La Plata, vol. 1, 

 1891. 



