12 Proceedings of the Biological Society of Washington. 



Subspecific characters. — Similar to Larus occidentalis occidentalis, but 

 mantle a darker plumbeous or deep neutral instead of plain neutral gray 

 and usually four outer primaries, instead of two, black basally without 

 gray areas. 



Description. — Pure white except mantle and wings. Head, neck, lower 

 parts, tail, its coverts, lining (except for cinereous primary coverts) and 

 edge of wing, tips of primaries, secondaries and tertiaries and a mirror on 

 first primary white ; mantle including whole outer surface of wing and 

 primary coverts dark plumbeous to neutral gray ; four outer primaries 

 black, the fifth showing gray wedges on both webs nearly to tip, with the 

 black reduced to a subterminal band on sixth, and the gray paler, remain- 

 ing primaries gray with broad white tips. Bill (in life) lemon yellow with 

 a red spot on lower mandible between angle and tip. Tarsi and feet (in 

 life) lemon yellow. Iris, hazel-brown. 



Measurements (in millimeters). — Male (10 adults): wing, 402-445 (416); 

 tail, 154-167 (162); tarsus, 67-72 (69); middle toe without claw, 58-62 

 (60); exposed culmen, 52-59 (55); depth of bill at base, 18-22 (20); at 

 angle, 20-23 (21). 



Female (8 adults): wing, 380-395 (389); tail, 147-153 (150); tarsus, 

 61-65 (63); toe, 52-58 (55); culmen, 46-53 (50); depth at base, 16-18 

 (17); at angle, 18-20 (19). 



Remarks. — While upwards of fifty specimens of the two races have been 

 examined, so many of them are either young, not fully adult, in moult, 

 unsexed or evidently wrongly sexed by inaccurate collectors that not more 

 than two-thirds of this material is wholly satisfactory. With a larger 

 series from southern localities, livens may prove to be a somewhat larger 

 race, although specimens of typical occidentalis from Oregon are quite 

 as large as the few birds examined from Lower California. 



The race livens is found breeding on both coasts of Lower California, 

 the Santa Barbara Islands and north to the Farallon Islands. Specimens 

 from the Farallones are fairly typical while, on the other hand, a bird 

 taken on July 20 at Trinidad, California, is the pale-mantled occidentalis, 

 like those from still farther north. 



There are reasons for suspecting that Audubon's specimens of occi- 

 dentalis were Herring Gulls, possibly vegoz, but it would be difficult to prove 

 this. His characters of bill, color of mantle and iris and pattern of prima- 

 ries fit livens, although the larger size and flesh-colored feet suggest vegce. 

 Both forms of occidentalis have yellow feet (the tarsus of the type of livens 

 is recorded by the collector as "lemon yellow") but the color of feet in the 

 gulls has caused endless trouble and it is unsafe to draw conclusions from 

 dried specimens as to what the color was in life. It seems to me the 

 discrepancies in Audubon's description do not justify the discarding of his 

 name occidentalis for the Western Gull. Apparently Schlegel (Mus. 

 Pays-Bas, VI, 1863, p. 15) was the first writer to correctly describe the 

 species as having yellow feet. 



In the natal down, juvenal, first winter and first nuptial stages of plumages 



