612 STEECORARIUS PARASITICUS, PARASITIC JAEGER. 



Stercorarhis parasiticus, ScHjEPF., Mus. Orn. 1779, 62, pi. 37 (/mscms).— Selys-L., Fn. Belg. 



1842, 155.— Gray, Gen. of B. iii, 1849, 653; List Br. B. 1863, 228.— Lawk., B. 



K. A. 1858, 839 ; Ann. Lye. N. Y. viii, 1866, 299.— Coites, Pr. Phila. Acad. 1861, 



243 ; ihid. 1863, 132 ; Pr. Ess. Inst, v, 1868, 305 ; Key, 1872, 309 ; Elliot's Prybi- 



lov Is. 1874.— Malm., J. f. 0. 1865, 205.— Newt., Ibis, 1865, 570.— Schl., Mus. 



P.-B. iv, 1863, 47.— Dall & Bans., Tr. Chic. Acad, i, 1869, 303.— Tuunb., B. E. 



Pa. 1869, 47. 

 Catharacla coprotheres, BrUnn., Orn. Bor. 1764, 38. 

 Zestris coprotheres, Des Mors, Tr. OiJl. 1860, 551. 

 Caiarractes parasita. Pall., Zoog. R.-A. ii, 1811, 310. 

 Lestria parasita. Keys. & Blas., Wirb. Eur. 1840, 95.— Bp., Cat. Met. Ucc. 1842, 80; Rev. 



Crit. 1850, 202.— Schl., Rev. Crit. 1«44, 85.— Midd., Sib. Reise, li, 1853, 241. 

 Cataracta cepphus, Leach., Syst. Cat. 1816, 39. 

 Stercorarius cepphus, Stbph., Gen. Zool. xiii, 1826, 211, pi. 23.— Sw. & Rich., F. B. A. ii, 



1831, 432.— Degl., Orn. Eur. ii, 1849, 295. (Not of authors.) 

 Stercorarius erepidaius, Vieill., Nouv. Diet. d'Hist. Nat. 1819, 155. (Nee Gm., Lath. ?) 

 Zestris crepidata, Temm., Man. 1815, 515.— Degl., Mem. Soc. Roy. Lille, 1838, 108.— 



SCHINZ, Eur. Fn. 1840, 390. (.Juv.). 

 Lestris richardsoni, Sw. & Rich., F. B. A. ii, 1831, 433, pi. 73.— Nutt., Man. ii, 1834, 319.— 



Bp., List, 1838, 63.— Eyt., Cat. Br. B. 1836, 51.— AuD., Om. Biog. iii, 1835, 503 ; 



Syn. 1839, 332; B. Am. vii, 1844, 190, pi. 452.— Tbmm., Man. iv, 1840, 499.— 



S'cHiNZ, Eur. Fn. i, 1840, 392.— Giu., B. L. I. 1844, 367.— Thomps., Nat. Hist. 



Ireland, iii, 1851, 394. 

 Cataravten richardsonii, Macgil., Man. ii, 1842, 257. 

 Stercorurhis richardsoni, Couics, Eev. Lestrid. Pr. Phila. Acad. 1863, 135. 

 Zestris ioji, schleepii, benickii, Brehm, V. D. 719, 720, 723. 

 (?) Lestris hardyi, spinicauda, Bp., Consp. ii, 1856, 210. (Blasius puts these under huffoni.) 



DiAG. St. rectricibus mediis rigidis, acuminatis, ultra cceteras 4-pollices porreatis ; tarsis suh- 

 asperis, 



Bai. — North Atlantic Ocean, and sea-coasts of Europe and America. Interior of 

 Arctic America. 



Adult, breeding plumage (No. 16802, Mus. Smithson.). — Bill much shorter than the head 

 or tarsus ; as high as broad at the base; basally rounded, compressed from nostrils to 

 tip ; rather robust, the sides converging from base to apex. Culmen broad, flattened, 

 scarcely appreciably convex to the unguis, which rises slightly above the level of the 

 ceiH, is moderately convex, tip not very strongly deflexed. Rami very long; gonjs 

 very short ; both somewhat concave in outline. Eminentia symphysis small but well 

 marked. Tomia of superior mandible at first ascending and a little concave; then 

 descending and a lit'le convex ; again, very decidedly concave as it decurves toward 

 the tip. Cere without oblique striae ; with a straight longitudinal sulcus on each side 

 of the culmen. Feathers extending far forward on superior mandible, with a curved 

 free outline, so broad that the feathers of the sides meet over the culmen. Feathers on 

 inferior mandible also project considerably, almost filling the triangular sulcus on the 

 side as well as the angular space between the rami. Middle of eye just over angle of 

 mouth. Wings moderately long, strong, pointed ; first primary much the longest ; rest 

 regularly and rapidly graduated ; all rather narrow and taperiug to an acute apex, 

 somewhat rigid and falcate. Secondaries short and inconspicuous ; broad, the tips of 

 the outer ones nearly square, of the inner obliquely incised, the apex being formed by 

 the inner web alone. Tertials long, soft, flexible. Tail moderately long, contained 

 not quite two and a half times in the wing; very slightly rounded, the graduation 

 l)eing only half an inch. Feathers moderately broad quite to their tips, which are 

 truncated. The central pair project three to four inches. They begin to taper about 

 four inches from their apices, and regularly converge to a very acute tip. Upper tail 

 coverts moderately long; the inferior still longer, but neither as long as in skua. Feet 

 rather short and quite slender ; tarsi as long as the middle toe and claw. Tibia naked 

 half an inch above the joint. The tcutellation and reticulation is the same as that 

 already described, but the nails are weaker and less arched, though fully as acute. A 

 decided occipital crest and a calotte. Nuchal region with the feathers acuminate and 

 rigid, with loosened fibrillte. Pileum, occipital crest, and whole upper parts deep 

 brownish-black, with a somewhat slaty tinge, and a slight but appreciable metallic 

 shade; this color deejiening into quite black on the wings and tail. Rhachides of 

 primaries and rectrices whitish, except at thoir tips ; the inner vanes albescent ))aso- 

 internally. Chin, throat, sides of head, neck all round, and under parts to the vent, 

 pure white ; the feathers of the latero-nnchal region rigid, acuminate, with discon- 

 nected fibrillae, light yellow. Under tail coverts like the upper parts, but somewhat 

 of a fuliginous tint ; the line of demarcation from the white of the abdomen very 

 trenchant. 



Xtarlg mature (No. 20144). — Size and form of the adult. Pileum and latero-nuchal 



