110 PLATALEID^E. 



do not extend very far. In summer they are found beside every marsh 

 and watercourse, briskly wading about in the shallow water and 

 plunging their long curved beaks downwards at every step. When 

 taking wing they invariably utter a loud ha ha ha, resembling hearty 

 human laughter, but somewhat nasal in sound. They frequently leave 

 the marshy places and are seen scattered about the grassy plains, feeding 

 like land-birds ; and on the pampas they often congregate about the 

 carcass of a dead horse or cow, to feed on the larvae of the flesh-fly in 

 company with the Milvago and the Hooded Gull. 



Their flight is singularly graceful ; and during migration the flocks 

 are seen to follow each other in rapid succession, each flock being 

 usually composed of from fifty to a hundred individuals, sometimes of a 

 much larger number. It is most interesting to watch them at such 

 times, now soaring high in the air, displaying the deep chestnut hue of 

 their breasts, then descending with a graceful curve towards the earth, 

 as if to exhibit the dark metallic green and purple reflexions of their 

 upper plumage. The flock is meanwhile continually changing its form 

 or disposition, as if at the signal of a leader. One moment it spreads 

 out in a long straight line ; suddenly the birds scatter in disorder, or 

 throw themselves together like a cloud of Starlings ; as suddenly they 

 again reform to continue their journey in the figure of a phalanx, half- 

 moon, or triangle. The fanciful notion can scarcely fail to suggest 

 itself to the spectator that the birds go through these unnecessary 

 evolutions intelligently in order to attain a greater proficiency in them by 

 practice, or, perhaps, merely to make a display of their aerial accomplish- 

 ments. The Glossy Ibis has another remarkable habit when on the wing. 

 At times the flock appears as if suddenly seized with frenzy or panic, every 

 bird rushing wildly away from its fellows, and descending with a violent 

 zigzag flight ; in a few moments the mad fit leaves them, they rise 

 again, reassemble in the air, and resume their journey. 



328. THERISTICUS CAUDATUS (Bodd.). 

 (BLACK-FACED IBIS.) 



Theristicus melanops, Darwin, Zool. Beagle, iii. p. 128 (Patagonia). Geron- 

 ticus melanopis, Scl. P. Z. S. 1871, p. 261. Theristicus melanopis, Scl. et 

 Salv. Nomencl p. 127 ; Durnford, Ibis, 1877, p. 190 (Buenos Ayres), et 1878, 

 p. 400 (Patagonia); Barrows, Auk, 1884, p. 272 (Azul). Theristicus 

 caudatus, Elliot, P. Z. S. 1877, p. 498. Ibis albicollis, Burm. La-Plata 

 Reise, ii. p. 510 (Parana, Mendoza, Tucuman). 



Description. Sides of throat and lores bare, skin black ; top of head and 

 lower part of neck- in front reddish chestnut ; neck white, a narrow line of 



