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



favorable environment of Southern California. We must, then, 

 almost of necessity conclude that the separation of the two faunas 

 is due to difference in time rather than to any other factor. 



The two horizons have in common with the Recent North 

 American fauna three cathartine genera, viz., Catliartes, Cath- 

 arista, and Gymnogyps. Catharista, at present foreign to the 

 immediate vicinity, is represented in the two deposits by distinct 

 species. Gymnogyps calif ornianus is abundant in the asphalt 

 beds and in the Recent fauna of a region including and extend- 

 ing far beyond both localities, yet the genus is represented in 

 the cave deposits only by a distinct species, G. ampins. It is 

 hard to explain how the cavern deposits could have been inter- 

 polated between the Rancho La Brea horizon and the Recent 

 and still possess two distinctive cathartine forms and only one, 

 Catliartes aura, in common with either of them. 



Distribution of Falconidae. — Palaeontology has added mate- 

 rially to our knowledge of this group in at least two respects, 

 namely in our concepts of the former distribution of its members 

 and of the degree of adaptive radiation that has taken place 

 within its limits. The three genera Geranoaetus, Norplants, and 

 Polybonts, limited in Recent time to tropical or to south tem- 

 perate America, are now known to have ranged in the previous 

 period well up into California. Geranoaetus went as far north 

 as Hawver Cave and the other two as far as Los Angeles. The 

 larger phase of Haliaetus, which is limited at present to the 

 northern parts of North America, had not at the time of deposi- 

 tion of the asphalt beds withdrawn to the northward as a 

 distinct geographical race. The remains of Haliaetus leucoce- 

 phalus from these beds embrace in their range of variation ex- 

 tremes of size surpassing at either end of the scale the two 

 existing races, H. I. alascanus and H. I. leucocephalus now geo- 

 graphically distinct. 



As illustrative of the number of adaptive radiations of the 

 eagle group we may point to the six fossil eagles of .Marsh, 

 Shufeldt, and Miller. These are as follows: Aquila sodalis, A. 

 pliogryps, A. dananus, Morphnus woodwardi, Geranoaetus grin- 

 nelli, and G. fragilis. Besides these extinct forms there were 

 found fossil the three persisting species Aquila chrysaetos, 



