734 SYSTEMATIC SYNOPSIS.— LONGIPENNES—GAVI^. 



heavy dark blotches. Nidiflcation normally terrestrial; reproduction altricial; young ptilo 

 paedio. 



Atialysis of SuhfamdUes, 



Bill epignathous, cered. (Jagers) Lestkidik^ 



Bill epignathous, not cered. (Gulls) Lakin^e 



Bill paragnathouB. (Teme) Stebnikje 



Bill hypognathouB. (Skimmers) EHYifCHOPiK^a: 



70. Subfamily LESTRIDIN^: Jagers, or Skua Culls. 



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

 *' c'ere," beneath the edges of which the nostrils open (unique, among water-birds) ; bill epigna- 

 thous. Tail nearly square, but the middle pair of feathers abruptly long-exserted. Feet 

 strong ; tibiae naked below, the podotheca granular or otherwise roughened behind, seutellate 

 in front ; webs fall ; claws large, curved, acute. 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. Another is that the sternum is single-notched behind, 

 there being two notches on each side in the other subfamilies. There is but one genus, and 

 only four species are well determined. They belong more particularly to the northern hemi- 

 sphere, 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 guUs ; eggs 2-3, dark-colored, variegated. The sexes 

 are aUke ; the young different, excepting one species ; there is also a particular melanotic plum- 

 age, apparently a normal special condition. At first the central tail-feathers do not project, 

 and they grow tardily. The skua guUs are eminently rapacious, whence their name of " jager" 

 (hunter) ; they habitually attack and harass terns and the smaller guUs, 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, they are able to acoomphsh the rapid and varied evolutions required 

 for the successful practice of piracy. Thus in their leading traits they are marine Eaptores ; 

 whilst the cered biU furnishes a curious analogy to the true birds of prey. 

 307. STERCOKA'BIXJS. (Lat. sfercoror-iMS, a scavenger.) JiGERS. Character of the subfamily, 

 as above. The species of Megalestris differs decidedly from the rest, and might form a genus 



apart. 



Analysis qf Species. 



Bill shorter than middle toe -without claw ; tarsus shorter than middle toe and claw ; central rectrices little 

 projecting, broad to the tip. (Megalestris.) 



Of great size, and robust form. Bill about 2 inches long s?eua 764 



Smaller; bill and tarsi relatively longer than in the foregoing, latter not shorter than middle toe and claw; 

 central rectrices finally projecting far beyond the rest 

 Central rectrices projecting about 4 inches, broad to the end . . . . pomatorhinus 766 



Central rectrices projecting about i inches, acuminate .... .... pcurasiticus 766 



Central rectrices projecting 8-10 inches, acuminate . . . biiffoni 767 



764. S, sku'a. (Pseroese name.) Skua. Bill shorter than the middle toe without the claw ; 

 exceedingly robust ; width at base about equal to the height, which is a third of the length of 

 culmen. Strise and sulci numerous and well marked. Encroachment of feathers on bUl 

 moderate, and nearly the same on both mandibles. Occiput scarcely crested. Wings only 

 moderately long for this subfamily ; the primaries very broad, and rounded at their tips. Tail 

 very short, broad, nearly even, the feathers truncated ; central pair projecting but little, and 

 broad to their very tips, which are also truncated. Feet large and stout; tarsi shorter than 

 the middle toe and claw. Size large; form robust and heavy; general organization very 

 powerful. Colors much the same over the whole body ; not subject to any very remarkable 

 changes with age, sex, or season. Adult $ ? ; Latero-nuchal feathers elongated, rigid, with 

 long disconnected fibrillse. Above, blackish-brown, more or less variegated with chestnut and 



