662 STEENIN^, TEENS. 



coverts white ; greater coverts slaty-gray [rtj-^o/sc'e], bordered with white. Tail deeply 

 loikLd ; the exterual pair of rectrices having au elongation not met with in any other 

 species of the subfamily. 



I regret exceedingly that I have had no opportunity of examining a specimen of this 

 rare and remarkable Gull. The Smithsonian has never received an example, and I am 

 not aware of the existence of one in any American collection. This is the more to be 

 regretted since the original description by Neboux, which has served as the basis of 

 nearly all subsequent accounts, both of American and European ornithologists, is brief, 

 delicient, and unsatisfactory. Fortunately, however, the species is one i^resenting snch 

 peculiar features, that no confusion has arisen concerning it. I have taken my diag- 

 nosis from the Zoology of the Voyage of the Venus, and compiled the above outline 

 description from Neboux's original account. I transcribe the further remarks of MM. 

 Pr(Svost and Des Murs : 



" In spite of the great difficulty usually experienced in determining the species com- 

 posing the genus Larus, on account of their close resemblance to each other, and the 

 many variations in colors which each presents, the one in question may be distinguished 

 at a glance by its orange eyelids and red legs and webs, and particularly by the two 

 white spots which ornament the forehead at the upper mandible; though the red feet 

 are indeed shared by several other species, e. g., L. hcematorhynchus King, and honapartei 

 Eichardson. We lay no stress upon the semicircular white spot on the under eyelid, 

 because this also exists in the franklini and honapartei of Eichardson. The two other 

 most striking and remarkable features of the species lie in the decurved bill, which is 

 a little like that of Larus modestits Tschudi ; and in the deeply forked shape of the tail, 

 ■which is elsewhere only found among typical Sternina-." 



Bibliography. — The species was lirst introduced by Neboux, as above, in 1840, under 

 the appellation of " La mouette a queue fourchue," no Latin binomial designation 

 being given. Upon this name and description MM. Prevost and Des Murs founded 

 in 1855 their Larus furcatus. In consequence, doubtless, of its forked tail, it was in 

 1653 referred by Bruch to the genus Xema. A distinct genus was first framed for it by 

 Bonaparte in 1854. 



Since the foregoing was penned I have been favored, through the courtesy of Howard 

 Saunders, esq., with au original description of a specimen in the British Museum. 

 Under date of March 6, 1873, Mr. Saunders writes me that the bird is a true Xema, and 

 has the appearance of being au Arctic sj)ecies. " Head, neck, and throat, of a sootier 

 color than in X. sahinei, darkening toward the base of the hood, but not forming a dis- 

 tinct black collar, as in this species ; a white frontal band ; under parts and tail pure 

 white, the latter more deeply torked than in sahinei ; mantle pale pearl-gray, somewhat 

 darker on the wing-coverts ; primaries blackish-brown on outer webs and continuation 

 of inner webs, thence white, except at tip ; secondaries white, tinged with gray at 

 their tips ; bill blackish, tipped with horn-yellow from the angle. Wing, 16.50 inches ; 

 tarsi, nearly 2 inches ; middle toe the same ; hind toe very small, but bearing a well- 

 developed claw." 



Subfamily Sternina. 



DiAG. Laridw rostro integro, paragnatlio. 



Ch. Bill entire, its upper and under mandible of equal length ; alwaj'^s compressed, 

 and higher than broad. Curve of culmen gentle and gradual from base to apes. 

 Commissure gently declinato-convex, sometimes slightly sinuate a>t base. Symphysis 

 of inferior mandibular rami much more extensive than in Lestridiiuv or Larina',, but the 

 eminentia symphysis less marked. Interramal s])ace narrow. Encroachment of feath- 

 ers on the bill as in Larinw. Nostrils linear-oblong, lateral, direct, pervious, varying 

 with genera as regards degree of approximation to the base of the bill. Wings ex- 

 tremely lengthened, narrow, and acute, the first primary much the longest, the rest 

 rapidly graduated. Secondaries .short and inconspicuous. Tail usually much elongated 

 and deeply forked, the lateral feathers being more or less attenuated and filiform ; only 

 occasionally short and broad {GelocheUdon), or gradnated {A)ious, &c.). Legs jilaced 

 rather further back, and less decidedly ambulatorial than iu Larincc. Tibia denuded 

 for a varying distance. Tarsi short and usually slender ; scutellate and reticulate, as 

 iu Larinw. Toes of moderate length, and of the usual relative ])roportious. Webs 

 rather narrow, and (except in Anous, &c.) more or less excised. Claws small, com- 

 pressed, but much curved and acute. Size moderate, or very small. General form 

 slender and delicate. Plumage as in other subfamilies, but the pterylaj narrow, the 

 sexes hardly differing in coloration, but the variations with age and season very great. 



For anatomical peculiarities of the subfamily, see under head of Sterna hiriindo. 



The generic and subgeneric groups of the Sternina) are rather better marked than 

 those of the Larinw. They are in number about thirteen. Of these more than half 

 (seven) are represented in North America. Fhwtliusa, Gygis, and several subgeuexa near 

 Anous are extralimital. The North American forms may readily be distinguished by the 

 following analysis. HydrQchelidon and Anous may be regarded as genera, the i-emaiuder 

 being subgenera of Sterna. 



