300 PROCEEDINGS OF THE ACADEMY OF 



San Francisco, collected in that immediate vicinity, would seem to demon- 

 strate the existence of the species on the Pacific as well as on the Atlantic 

 coast. The specimens I have compared critically with an eastern series, and 

 have been unable to detect the slightest difference. They appear to be abso- 

 lutely identical. A circumstance that would seem to confirm the belief that 

 the present species does extend quite across the continent is the fact that 

 there are undoubted specimens in the collections of Messrs. Kennicott and 

 Ross from localities whose general avi-fauna is rather of a western than of an 

 eastern type. Should the existence of this bird on the Pacific slope be satis- 

 factorily demonstrated, its habitat may properly be given as the "Continent 

 of North America." 



I beg leave to dedicate this species to that Institution whose material for 

 the illustration of North American ornithology, unequalled in richness and 

 extent, has so greatly increased our knowledge in this department of Natural 

 History. And the name seems not inappropriate, for, as there is scarcely a 

 lake or river in North America which does not furnish sustenance to this Gull 

 at some period of its extensive migrations, so there is hardly a locality, how- 

 ever remote or inaccessible, which has not yielded its varied productions to 

 the Smithsonian Institution, until its collections afford every facility for the 

 study of the Natural History of our Continent. 



II. A large white apical space on first primary in adult birds. Legs dusky 

 olivaceous, the webs bright chrome. 



9. Larus Califoknicus Lawrence. 



L. argentatoides, Bp. 1828 et Richardson, 1831; nee Brehm. L. Cali- 

 fornicus, Lawr. 1854 et 1858. Laroides Calif. Bp. 1856. 



Sp. char. Bill moderately stout and strong, the angle well developed ; 

 varying considerably in size, larger than in Delawarensis, sometimes nearly 

 equalling argentatus. Tarsus equal to or slightly longer than the middle toe 

 and claw. Adult : Bill chrome yellow, tinge with greenish, a vermillion 

 spot on the lower mandible at angle ; a black spot just above it, forming with 

 another small black spot, sometimes present on the upper mandible, an im- 

 perfect band. Legs olivaceous greenish or yellowish, the webs chrome. Mantle 

 pearl blue, much as in brachyrkynchus, lighter than in canus (Linn.), perhaps a 

 little darker than in argentatus. Primaries: bases of all light bluish white, almost 

 white internally, especially on the outer ; and of great extent en all the prima- 

 ries ; first with a white space at the end about two inches long, the shaft white 

 along the white portion of the feather ; second with a white spot near the end. 

 on the whole of the inner and most of the outer web, divided by the black 

 shaft ; tips of all white ; black forming merely a narrow subterminal band on 

 the sixth. Tips of inner primaries, of the secondaries and tertials, white. Di- 

 mensions, (average, for they vary greatly) wing 15-50 ; bill nearly 2-00 ; tar- 

 sus 2-30. Female smaller. 



Habitat. California ; Pacific coast ; Arctic America, internally ; breeds 

 about Great Slave Lake. 



The following is the argument in favor of the synonymy adduced : 



In the first place, argentatoides of Bonaparte's Synopsis (1^28), and of Rich- 

 ardson (1831), are the same bird, since the latter quotes the former as au- 

 thority for the name, and the diagnosis and descriptions of the two agree 

 perfectly. Now, in the collection there are numerous specimens of the fully 

 adult bird from Arctic America, from localities not far distant from those 

 where Richardson's specimens were procured. These specimens agree pre- 

 cisely with Richardson's descriptions of argentatoides,* and correspond very 



* If it be objected that the expression " six outer quills crossed by a brownish black 

 bar, which t.ikes in nearly the whole of the first one'' is not correct, I refer to several 

 other descriptions of Richardson, (his canus and others,) where it is evident that he does 



[June, 



