1 



308 LAEID^, GULLS, TEENS, ETC. GEN. 279-80. 



cious and distensible ; there is no special crop ; the proventriculus is a bulging of 

 the gullet ; the gizzard is small and little muscular ; the coeca are variable ; the 

 cloaca is large. Certain genera ofier peculiarities of this general type of alimentary 

 canal. According to Nitzsch, the pterylosis of the gulls "approaches very closely 

 that of the Scolopacidrn, and can hardly be distinguished therefrom with certainty 

 by any character." In the terns, " in consequence of the slender and elegant form 

 of the body, the tracts are very narrow, and perfectly scolopacine." The jaegers 

 differ "in having the outer branch of the inferior tract united with the main stem 

 in the first part of its course, and all the tracts still broader and stronger than in" 

 the gulls ; while in the petrels, " the tract formation of the jaegers is elevated into 

 the type of a group, undergoing scarcely any change in the form of the inferior 

 tract, but showing some little modification of the dorsal tract." 



As here constituted, the order embraces two families, to be known by the char- 

 acter of the nostrils ; both are well represented in this country. 



Family LARID^. Gulls, Terns, etc. 



Nostrils not tubular (linear, linear-oblong, oval or drop-shaped), sub-basal or 

 median, lateral, pervious. The hallux, though very small and elevated, with its tip 

 hardly touching the ground, is, except in one instance, better developed than in the 

 petrels. The habitat is fluviatile, lacustrine and maritime, rather than pelagic. 

 The family contains four leading genera, each of which may be assumed as the 

 basis of a subfamily ; all four occur in North America. 



Subfamily LESTBIDIN^. Jal'gers, or SJaia Gulls. 



Covering of bill discontinuous, the upper mandible being saddled with a large 

 horny " cere," beneath the edges of which the nostrils open (unique, among water- 

 birds) ; bill eiDignathous. Tail nearly square, but the middle pair of feathers 

 abruptly long-exserted. Feet strong, the podotheca granular or otherwise roughened 

 behind, scutellate in front ; webs full. Certain pterylographic characters have been 

 already noted. A leading anatomical peculiarity in the large size of the coeca, as 

 compared with the cases of the other subfamilies. There is but one genus, and only 

 four species are well determined. Thej' belong more particularly to the northern 

 hemisiDhere, although some also, inhabit southern seas ; they mostly breed in 

 boreal regions, but wander extensively at other seasons. They inhabit sea coasts, 

 and also large inland waters ; the nidiflcation resembles that of the gulls ; eggs, 

 2-3, dark-colored, variegated. The sexes are alike ; the young different, excepting 

 one species ; there is also a particular melanotic plumage, apparently a normal 

 transient condition. At first the central tail feathers do not project, and they grow 

 tardily. The skua gulls are eminently rapacious, whence their name of "jaeger" 

 (hunter) ; they habitually attack and harass terns and the smaller gulls, until these 

 weaker and less spirited birds are forced to drop or disgorge their prey. Their 

 flight is vigorous ; lashing the air with the long tail, thejr are able to accomplish the 

 rapid and varied evolutions required for the successful practice of piracy. Thus 

 in their leading traits they are marine Kaptores ; whilst the cered bill furnishes a 

 curious analogy to the true birds of prey. 



279-80. Genus STERCORARIUS Brisson. 



* Bill shorter than middle toe without claw ; tarsus shorter than middle toe and 

 claw ; central rectriccs little projecting, broad to the tip. {Buphagns.') 



