218 AVES : LONGIPENNES. — XXXII. 
W. 81. T. 34. B. 1}. N. Atl, S. to Conn, (Eu.) (An old 
name.) 
326. PLAUTUS Briinnich. (mAs, swimmer.) 
640. P, impennis (L.). Grear Aux. Black above; lower 
parts and tips of secondaries white. L. 29. W. 5%. B. 3}. N, 
Atl., formerly S. to Mass.; now wholly extinct. ‘ His Grace, the 
Auk, who lost the use of his wings, and perished off the earth in 
consequence.” (Coues.) (Lat., wingless.) 
327. ALLE Link. (Swedish name.) 
641, A. alle (L.). Dovexre. Upper parts black, the second- 
aries tipped with white ; sooty-brown in summer. L.8. W. 4$. 
B.}4. Arctic, S.toN.J. (Eu.) 
OrveR XXXII. LONGIPENNES. (Tue Lone-wingep 
SwIMMERS.) 
Feet palmate; tibia feathered; legs inserted near the centre of 
equilibrium so that the bird stands with the axis of the body nearly 
horizontal; hind toe small and elevated, sometimes wanting. Bill 
usually long, horny, not serrate nor lamellate; nostrils developed, not 
tubular; no gular pouch. Wings very long and pointed; tail well 
developed. Palate schizognathous. Altricial. Water birds, of 
great powers of flight, feeding chiefly on fishes. 
a. Bill with the lower mandible not produced nor specially compressed. 
6. Covering of upper mandible in three parts, a hook at tip, a sort of cere 
overhanging nostrils, and a lateral piece. . . STERCORARUDA, 127. 
bb. Covering of upper mandible of a single piece pierced by the nostrils. 
Larip#, 128. 
aa. Bill with the lower mandible much longer than upper, the terminal part 
of both mandibles much compressed, like a knife-blade. 
RuHYNCHOPIDZ, 129, 
Famity CXXVU. STERCORARIIDAl. (THE Jacers.) 
Gulllike birds, with the bill hooked and “cered;” tail square, 
with the middle pair of feathers long-exserted; tibia naked below; 
tarsus scutellate in front, granular behind. Two genera with 4 
species, “marine Raptores,” large, vigorous, rapacious, living by 
robbing the terns and smaller gulls. 
a. Depth of bill at base at least half length of upper mandible (measured along 
side); tarsus shorter than middle toe and claw; tail short, nearly even. 
Mrcatxsrats, 328. 
aa. Depth of bill at base not half length of upper mandible; tarsus longer 
than middle toe and claw; middle tail feathers (in adult) very long. 
STERCORARIUS, 329. 
328. MEGALESTRIS Bonaparte. (uéyas, large; Ayorpis, pirate.) 
642. M. skua (Briinnich). Sxua Gui. Grayish-brown, L. 
22. W.16. B.2. N. Atl. rarely 8. to Mass. (Eu.) (Feroése 
name.) 
