506 GULL TRIBE. 



figured species (Attagis latreillei) inhabits the Falkland Islands and the higher 

 mountains of the southern part of South America. In both genera the beak is 

 rather short and compressed, with the aperture of the nostrils in most cases closed 

 by a horny membrane covered with short feathers. Generally these birds are met 

 with in pairs or small coveys of five or six, which frequent the same spots for long 

 periods. Although they frequent desert regions, the nest is placed near a lake ; 

 the number of eggs being four or five. 



THE GULL TRIBE. 

 Order GAVI.E. 



Formerly associated with the petrels, the terns, skimmers, gulls, and skuas, 

 are now generally regarded as nearly allied to the Limicolce, with which they agree 



in the arrangement of their plumage. 

 Externally these birds are characterised 

 by the prevalence of pure grey and white 

 in their adult plumage, and by the com- 

 plete webbing of the three front toes, as 

 well as by their long wings, in which the 

 fifth secondary quill is wanting. Their 

 skulls differ from those of the typical 

 Limicolce in the absence of basipterygoid 

 processes on the inferior surface of the 

 rostrum; while the hinder extremity of 

 the lower jaw is abruptly truncated; and 

 in the wing the flat bone, corresponding 

 to the first joint of the human forefinger, 

 has two circular perforations a feature 



distinguishing the skeleton from that of any of the plover tribe and their allies. 

 Throughout the group there are deep grooves on the upper surface of the skull for 

 glands ; the development of these being very variable among the Limicolw. Except 

 in the skimmers, the beak is simple, and may be either straight or hooked. In 

 the wing there are ten large primaries, and one minute and concealed ; the whole 

 plumage is remarkably compact, the contour-feathers having after-shafts: there 

 are twelve tail-feathers ; the spinal feather-tract is well defined by bare lateral 

 areas on the neck, and forked on the upper-back ; and the oil-gland is tufted. In 

 their down-clad and active young, these birds resemble the plovers, but the down 

 is of a more complex type. The first toe is raised above the level of the others, 

 with which it is not connected by membrane ; and the nasal apertures in the skull 

 are schizorhinal, while the external nostrils are elongated, and placed rather low 

 down on the sides of the base of the beak. In the general structure of the palate, 

 as well as in the presence of a process on the outer side of the humerus (see figure 

 in Vol. III. p. 295), the gulls resemble the plovers. Rarely, if ever, exceeding 

 three in number, the eggs are spotted or scrolled with dark markings on the light- 

 coloured ground. 



YOUNG GULLS COVERED WITH DOWN. 



