616 STERCOKARIUS BUFFONI, LONG-TAILED JAEGER. 



DiAG. S. rectvicibus mediis ultra cccteras 8 ad 10 poll, porrectis. 



Hah. — Coasts of North America and Europe, chiefly in higher latitudes. Interior of 

 Arctic America. 



Adult, breeding plumage. — Bill shorter than the head, less than the middle toe without 

 the claw ; stout, compressed, higher than broad at the base, its sides regularly con- 

 verging. Ceral poriiou of culnieu broad, flat, depressed, slightly concave in outline; 

 ungual portion very decidedly declinato-convex to the greatly overhanging tip ; nar- 

 rower than the ceral. Toniia of superior mandible sinuate ; at iirst concave and ascend- 

 ing ; then convex and descending ; again very concave as they decurve toward the 

 deflected tip, just iiosterior to \j'hich there is an imperfect notch. Tomia of inferior 

 maxilla nearly straight to the tip, where they are decurved. Gonys very short, slightly 

 concave in outline. Emiuentia symj)hysis acute, but not very large ; rami very long 

 as compared with the gonys, but absolutely rather short, from the encroachment of the 

 feathers. Cere very short, being scarcely if at all longer than the unguis ; its lower bor- 

 der curviug upward to give passage to the nostrils. The encroachment of the feathers 

 on the bill is greater than that of any other species ; on the upper mandible they ex- 

 tend within half an inch of the distal end of the cere, having a broad, rounded termi- 

 nation, the feathers of the two sides meeting on and coveriug the culmen some distauce 

 from its real base. The feathers on the sides of the lower mandible extend nearly as 

 far as on the upper, and those between the ran i quite to the sympliysis. Wings ex- 

 ceedingly long ; first primary much the longest ; rest rapidly graduated ; all rather 

 narrow, tapering, falcate, actually pointed, their rhachides stift' and strong. Second- 

 aries short and inconspicuous ; rather broad ; their apices as in the other species. 

 Tertials moderately long, very straight, flexible, rounded at their extremities, the 

 edges of their vanes convoluted. Tail very long ; longer, both absolutely and rela- 

 tively, than in any other North American species, being half as long as the wings; 

 graduated, the lateral feather beiug three-fourths of an inch shorter than the next to 

 central pair ; all the feathers moderately broad, converging somewhat to their rather 

 broad, rounded tips. Central rectrices extremely lengthened, exceeding the wings; 

 projecting 8 to 10 inches beyond the tips of the lateral ones. They are extremely rigid 

 at the base, being there much stifler than the other feathers, but gradually become 

 flexible, and at length filamentous in character, but preserve great elasticity through- 

 out. They are about the same as the other feathers at their bases ; thence taper uni- 

 formly to their exceedingly acute tips. Their edges are sinuate Superior tectrices 

 moderately long ; the inferior reaching nearly to the tips of the rectrices. Feet quite 

 slender ; tarsus equal to middle toe and claw. Tibise bare of feathers for three- 

 fourths of an inch. The reticulation of the feet is identical with that alreadj' des- 

 cribed under other species. The scutella of the anterior face of the tarsus, however, 

 show a tendencj' to degenerate into minute plates near the tibio-tarsal joint. Propor- 

 tions of the toes as in other species, but the claws are comparatively small and weak, 

 and but moderately curved and acute. 



Occiput decidedly subcrested. The latero-nuchal region has its feathers length- 

 ened, with disconnected fibrillaj, but they are hardly acuminate or rigid. The plum- 

 age about the bill is short, thick, and compact ; that of the upper parts is soft and 

 flexible, only moderately imbricated and compact ; that of the under parts is long, soft, 

 and very thick. 



Bill dusky, its nail almost black. Tarsi deep leaden-blue ; tibia% phalanges, interdig- 

 ital membranes, and claws black. Occiput subcrested, more decidedly than in any other 

 species, forming a calotte of brownish-black, which color extends downward on the 

 cheeks, the feathers before and below the eye and on the sides of the bill being of this 

 color. Neck all round, but especially the sides of the head and the peculiarly-formed 

 feathers on the latero-nuchal region, light straw-yellow. Whole upper parts, with 

 upper wing and tail coverts, deep slate, which, on the primaries, secondaries, lateral 

 tail feathers, and distal half of central pair, deepens into a lustrous brownish-black. 

 Under surface of wings and tail deeper slate than the black, but not so deep as the 

 upper surfaces. Chin, throat, and upper breast white, gradually becoming obscured 

 with dusky-plumbeous, which deepens posteriorly, so that the abdomen and under tail 

 coverts are nearlj^ as dark as the back. Rhachides of first two or three i>rimaries pure 

 white, deepening into brownish-black at their tips ; of the other primaries, and of the 

 tail feathers (including the central pair), brown, except just at the base, blackening 

 terminally. Under surfaces of all the rhachides are white for nearly their whole length. 



Diine)ibions. — Length of culmen, 1.15 inches; gape, 1.70; cere, 0.60; unguis about the 

 same; gonys, 0.30; from feathers on sides of bill to tip, 0.90 ; wing, 12.50 ; tail, 6.25; 

 central pair, 14.00 to 16.00 ; the projection, 8.00 to 10.00 inches ; tibiie bare, 0.75 ; tarsus, 

 l.GO ; middle toe without claw, 1.40. 



The changes of plumage of this species being exactly like those of S. parasiticus, it 

 is unnecessary to repeat them. 



Synongmii. — As already renuirked, while speaking of S. parasiticiis, it is exceedingly 

 difficult to determine to which of the two species of Jiiger the names "jjar«iitio«s" and 



