109* BIRDS OF ILLINOIS. 



the bill sometimes blackish. Young: Uniform, rather dark, grayish brown, the rump, 

 upper tail-coverts, basal half of tail, and entire lower parts, including axillars and lining of 

 the wing, continuous white; head and neck streaked with dusky or grayish brown on a 

 grayish or dull whitish ground-color. Feathering of the head extending forward almost 



to the bill. 



Length, about 24.00-26.00; expanse, about 40.00; wing, 10.30-11.75; tail, 4.00-5.00; culmen, 

 4.15-G.30; depth of bill, .60-72; tarsus, 3.10-4.00; middle toe, 2.15-2.70; bare portion of tibia, 

 2.00-2.S0. 



Downy young. "The young birds are at first covered with a thick down of a dark gray 

 color." (Audubon.) 



Immature specimens show, according to age, all possible 

 stages of plumage intermediate between the pure white adult 

 and gray young. 



I have very little information respecting the White Ibis in 

 Illinois, having observed it but once, a flock of seven or eight 

 examples, all in the gray plumage, having been seen by Mr. 

 William Brewster and myself about the 8th of May, 1878, fly- 

 ing along the Wabash River, at Mt. Carmel. 



Genus PLEGADIS Kaup. 



"Falcinp.Uus Bechst." Auct. (ncc Bechstein). 



Plegadis Kaup, Skizz. Entw. Gesch. 1829, 82. Type, Tantalus falclnellus LlNN. 



Tantalides Wagl. Isis, 1832, 1231. Type, Tantalus falclnellus Linn. 



Gen. Chab. Bill shallow through tho base, moderately tapering, and gently curved; 

 the base not turgid, and the basal outline of the maxilla deeply concave; bare portion of 

 tibia equal to or longer than outer toe; middle toe about three fourths the tarsus; inner toe 

 reaching past the subterminal articulation of the middle toe; hallux about equal to the 

 basal phalanx of the inner toe. Forehead and orbital, malar, and gular regions completely 

 feathered, the lores and interramal space only being naked, the feathering on the chin 

 forming an acute angle which advances to as far as the middle of the nostrils; feathers of 

 the pileum elongated, lanceolate, and distinct, forming, whon erected, a sort of full, round- 

 ed crest; those of the occiput and nape, and upper half of the neck all round, also distinct 

 and lanceolate. Plumage chiefly metallic green above: the adults with head and upper 

 part of neck chestnut, and lower parts chestnut {autumnalis and guarauna) or violet- 

 blackish (ridgwayi); the young with head and^upper part of neck streaked grayish brown 

 and white, the lower parts grayish brown (autumnalis and guarauna) or violet-dusky 

 (ridgwayi). 



This genus differs conspicuously from Guara in the complete feathering of the head 

 (excepting only the lores and tho space between the mandibular rami) and in the brilliantly 

 metallic plumage. 



There are two species in North America, one, P. autumnalis, 

 inhabiting the eastern portion, and identical, apparently, with 

 the Old World species, the other, P. guarauna, replacing it in 

 the western parts of the United States and southward through 



