90 University of California Publications in Geology [VOL. 7 



At Rancho La Brea there occur six truly cathartine species 

 as follows: Gymnogyps calif ornianus, Sarcorhamphus clarlci, 

 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, 

 Catliarista 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 calif orni- 

 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 

 Catliarista 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 Pacific 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 11 individuals 



Cathartes aura 20 individuals 



Catliarista 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 



