THE SKUA-GULLS. 537 



FAMILY LARIDJ2. THE GULLS. 



Bill generally shorter than the head, straight at the base, and more or less curved 

 at the end; nostrils linear; head ovate; neck short; body rather full and compact ; 

 wings long and pointed; legs of moderate length, strong, and covered anteriorly 

 with transverse scales ; feet fully webbed, the hind toe small and elevated. 



Birds of this family frequent the shores of the ocean, but often wander to great 

 distances from land ; they are incapable of diving, but swim buoyantly. Their food 

 consists principally of fish and Crustacea ; but some of the larger species feed occa- 

 sionally on the flesh of cetaceous animals, and devour the young and eggs of some 

 species of sea-birds. 



The family of Laridce is divisible into four sub-families, with the following char- 

 acters : 



LESTRIDIN^:. Basal half of upper jaw with a horny covering, distinct from the 

 tip, and under which the nostrils open considerably beyond the middle of the bill ; 

 bill abruptly and much decurved at the tip ; tail cuneate ; body full, stout. 



LARIN.E. Covering of the bill continuous ; anterior extremity of nostrils gen- 

 erally reaching to the middle of the bill ; culmen considerably decurved towards the 

 tip ; body robust ; tail generally even. 



STERNIN^E. Covering of bill continuous ; nostrils opening in the basal third of 

 the bill; culmen gently curved to the tip of the lengthened and attenuated bill; 

 body rather slender ; wing lengthened ; tail usually deeply forked. 



RHYUCHOPIN^B. Bill excessively compressed, like the blade of a knife; lower 

 jaw much longer than the upper; the point obtuse; body slender; tail forked. 



Sub-Family LESTRIDINJE. The Skua -Gulls ; the Jcegers. 



Bill strong and much curved at the end, the base covered with a membranous 

 cere; wings lengthened; tail cuneate, with the two central feathers projecting. 



These hardy birds inhabit the high latitudes of both hemispheres. There are 

 four Arctic species found both in Europe and North America. They are piratical in 

 their habits, appearing to derive their subsistence mainly from the labors of others. 

 They chase and harass various species of Gulls, compelling them to disgorge a por- 

 tion of their food, which they dart after, and seize before it reaches the water. 



STERCORARIUS, BEISSON. 



Stercorarius, Brisson. Ornithologie (1760). 



Bill rather strong; the culmen straight, and covered at the base with a smooth 

 cere, the end curved ; nostrils linear, and more open anteriorly ; wings pointed ; first 

 quill longest; tail of moderate length; the two middle feathers elongated; tarsi 

 strong, and covered with prominent scales; claws sharp and much curved; feet 

 fully webbed; hind toe short, and but little elevated. 



