92 University of California Publications in Geology [V0.7 
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., Cathartes, Cath- 
arista, and Gymnogyps. Catharista, at present foreign to the 
immediate vicinity, is represented in the two deposits by distinet 
species. Gymnogyps californianus is abundant in the asphalt 
beds and in the Recent fauna of a region including and extend- 
ing far beyond both loealities, yet the genus is represented in 
the cave deposits only by a distinct species, G. amplus. 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, 
Cathartes 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 Geranoaétus, Worphnus, and 
Polyborus, 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. Geranoaétus went as far north 
as Hawver Cave and the other two as far as Los Angeles. The 
larger phase of Haliaétus, 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tion of the asphalt beds withdrawn to the northward as a 
distinet geographical race. The remains of Haliaétus 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. 1. alascanus and H. l. lewcocephalus now geo- 
eraphically 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, Geranoaétus grin- 
nelli, and G. fragilis. Besides these extinct forms there were 
found fossil the three persisting species Aquila chrysaétos, 
