734 SYSTEMATIC SYNOPSIS. — LONGIPENNES — GAVI^. 
heavy dark blotches. Nidification normally terrestrial; reproduction altricial; young ptilo- 
paedic. 
Analysis of Subfamilies. 
Bill epignathous, cered. (Jagei's) . Lestkidin^ 
Bill epignathous, not cered. (Gulls) Larin^ 
Bill paragnatbous. (Terns) STKRNiKiE 
Bill bypognathous. (Skimmers) , Rhynchopin^ 
70. Subfamily LESTRIDIN>E: Jagers, or Skua Culls. 
Covering of bill discontinuous, the upper mandil)le being saddled with a large horny 
cere," 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, scutellate 
in front ; webs full ; 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 nidification 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 plum- 
age, apparently a normal special condition. At first the central tail-feathers do not project, 
and they grow tardily. The skua gulls are eminently rapacious, whence then- name of " jager " 
(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, they are able to accomplish the rapid and varied evolutions required 
for the successful practice of piracy. Thus in their leading traits they are marine Raptores ; 
whilst the cered bill furnishes a curious analogy to the true birds of prey. 
307. STERCORA'RIUS. (Lat. stercorarius, a scavenger.) Jagers. Character of the subfamily, 
as above. The species of Megalestris differs decidedly from the rest, and might form a genus 
apart. 
Analysis of 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 skua 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 765 
Central rectrices projecting about 4 inches, acuminate parasiticus 766 
Central rectrices projecting 8-10 inches, acuminate hvffoni 767 
764. S. sku'a. (Faeroese 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 
culm en. Striae and sulci numerous and well marked. Encroachment of feathers on bill 
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, M^hich 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 $ 9 '■> Latero-nuchal feathers elongated, rigid, with 
long disconnected fibrillae. Above, blackish-brown, more or less variegated with chestnut and 
