Female. Head above, and occipital tuft and body above, pale reddish or purplish brown, with a tinge of cinereous; every feather with transverse irregular bars and lines of black, and with a conspicuous longitudinal narrow stripe of yellowish white in the centre. Throat pale white; inferior surface of the body pale purplish brown on the belly and flanks, with irregular lines and minute spots of black. Hab. Mexico and Texas. Spec. in Mus. Acad. Philada. Obs. The descriptions by M. Lesson and Mr. Vigors, as cited above, were published nearly at the same time. That by M. Lesson appears to have had a short period of priority, which entitles his name to preference. In our article on another species, we propose to give a synopsis, with descriptions of all the partridges inhabiting the continent of America. LARUS HEERMANNI.—Cassin. The White-Headed Gull. PLATE V.—Adult Male and Young female. Amongst the many species of sea-birds which frequent the coast of the American continent on the Pacific ocean, there is a race of Gulls with very graceful forms, slender and brightly colored bills, and handsome plumage, of which no immediate representatives have yet been discovered on the eastern shores of this continent. The range of the species of this race extends from Oregon to Cape Horn, and one species similar in general characters inhabits the coasts of Australia and some of the islands in the Pacific ocean. This group appears to be characterized generally by the uniform lead-colored plumage which prevails in several of the known species, and seems to embrace _Larus Belcheri_. Vigors. _Larus fuliginosus._ Gould. _Larus nova hollandiæ._ Stephens, the present species, and some others. The bird, which is the subject of the present description, is one of the most handsome of the numerous family to which it belongs, and of which species are found on all the sea shores of the world. It is one of many additions to the ornithological fauna of the United States, which have been discovered by Adolphus L. Heermann, M. D., of Philadelphia, who has been occupied for nearly three years in making researches and collections, with excellent judgment and great enterprise, in California, and has now succeeded in safely bringing home the most extensive collections ever made in that country. Dr. Heermann found this Gull occurring frequently on the coast of California, but most numerous in the harbor of San Diego in the month of March, at which time though it appeared to have attained its perfect plumage in some instances, yet many specimens were clothed in that of young birds. Both of these stages of plumage are represented in our plate, and it is possible that the plumage assumed in winter, at all ages, may be similar in most respects to that of the young. [Illustration: Plate 5 The White-headed Gull Larus Heermanni (_Cassin_)]