82 
Ridgway on the American Vultures. 
Pseudo^ryphus californianus. This species appears to 
have become excessively rare in California, having been nearly, if not 
quite, exterminated in many parts of the State, through the agency 
of poisoned carcases exposed for the destruction of bears and 
wolves (cf. Henshaw, Ann. Rep. Geog. Surv. W. 100th Merid., 1876, 
p. 265). It may not, perhaps, be generally known, — at least the 
fact has been almost wholly overlooked by authors, — that this spe- 
cies is fully the peer of the Condor in size, the length of the wing 
and tail averaging even decidedly greater. It is not, however, 
quite so strongly built, the beak and feet being proportionately 
weaker. Apropos of the wide disagreement of authors as to the 
alar expanse of the Condor, I have been led to try a very simple 
method of determining what should be the stretch of wing in that 
species and P. californianus , • with a result which is undoubtedly 
approximately correct. This method is based upon measurements 
of the wing bones of these two species and Cathartes aura , and the 
application of the “ Rule of Three,” as follows. 
The maximum length of wing in G. aura is 23 inches, the humerus 
measuring 6.00 inches, and the ulna and radius 7.25 inches, making 
the total length of one outstretched wing 36.25 inches. The maxi- 
mum alar expanse of this species is 6 feet, or 72 inches. In S. 
gryphus and P. californianus the maximum total length of wing is 
55.50 and 58.25 inches, respectively. Therefore, assuming that the 
primaries have about the same proportionate length in the three 
species, we have, by applying the aforesaid rule, the following 
result : — 
Sarcorhamphus gryphus (length of outstretched wing, 55.50 inches). 
36.25 : 72 : : 55.50 : 110.23 = 9 feet 2 inches. 
Pseudogryphus californianus (length of outstretched wing, 58.25 in.). 
36.25 : 72 : : 58.25 : 115.65 = 9 feet 8 inches. 
Allowing for individual variation in both species, the average 
alar expanse of each may be set down at about 9 feet, P. cali- 
fornianus , at least, perhaps sometimes reaching 10 feet, while it is 
quite certain that the largest individuals of either would not much 
exceed, if indeed they reach, an extent of 10 \ feet. 
For sake of comparison I give below measurements of certain 
bones of S. gryphus , P. californianus , and G aura, taken from fully 
adult examples of each. 
