90 University of California Publications in Geology [Vou.7 
At Rancho La Brea there occur six truly cathartine species 
as follows: Gymnogyps californianus, Sarcorhamphus clarki, 
Cathartornis gracilis, Pleistogyps rex, Cathartes aura, and Cath- 
arista occidentalis. Besides these forms, the aberrant Teratornis 
is nearer to the Cathartidae than to any other family at present 
recognized. In the cave deposits there appear the two forms, 
Catharista shastensis and Gymnogyps amplus, belonging to ex- 
isting genera. 
The condors and Teratornis represent the extreme of spe- 
cialization in point of size, the greatest degree of diversity, and 
possibly also the least specific longevity. Gymnogyps californi- 
anus alone of the six larger forms has persisted unchanged from 
the time of formation of the asphalt beds, where it is the most 
abundant of the condors, until the present time, when it seems 
on the verge of extinction. Probably its associates of that time 
had passed the prime of their specific existence while the present 
form, less specialized toward gigantism, constituted a younger 
development reaching its maximum of virility later than its 
congeners but becoming decadent by the present time. 
As a result of the excavations at Rancho La Brea the genus 
Catharista became known to the Pleistocene of North America, 
its first discovery in the fossil state. Its range was at the same 
time extended from its previous limits—the tropical and lower 
Austral zones of both continents—to include the Pacifie Coast 
region of California, an area at present occupied by an Upper 
Sonoran fauna. The fossil species C. occidentalis is found in 
great abundance in the asphalt. Its relative abundance as com- 
pared with the other vultures there is shown by a census of an 
unassorted collection of the bird remains, which gave the fol- 
lowing results: 
Gymnogyps Californianus  ..........-.2---------- 11 individuals 
Cathartes aura 20 individuals 
Catharista occidentalis 21 individuals 


As indicated in the note descriptive of Catharista occidentalis, 
the difference between the fossil and the Recent forms lies in the 
greater body size of the fossil form accompanied by a difference 
in proportion of the segments of the posterior limb. The tarsus 
Polyborus there appear the following fossil forms whose nearest 
