132 ORTHOGENETIC EVOLUTION IN PIGEONS. 



In view of these facts the question of the origin of ocelli should be revised from 

 the standpoint of the dark central spot as a primitive avian character. In consider- 

 ing this subject, Darwin took "gradual evolution" as his principle, and did not go 

 far into the development of the various components of the ocellus, beyond compar- 

 ing all of the conditions found in adult species. He was thus led to the view that the 

 peacock's ocellus arose by the coalescence of two ocelli. Kerschner 34 has made a 

 much more detailed study of the development of the ocellus. He finds a coalescence 

 of black bars, and records a number of observations concerning regions and direc- 

 tions of color-transformation Iwhich have a bearing upon the principles which I 

 have found to apply to many [characters, and in several different families of birds. 

 Kerschner starts with bars of black and yellow, which are supposed to arise from 

 a "yellowish-brown, dark-gray, speckled condition." I am confident that this 

 earlier condition is a feather with a dark center. 



34 Zeit. f. wiss. Zool., vol. 44. 1886. 



EXPLANATION OF PLATE 66. 



Phasianus wallachii. Toda del., 1904, after Elliot (Monograph of the Phasianidse, vol. n). 

 The descriptions are those of Elliot: 



A. "Male. Top of head and lengthened crest dark brown. Neck, back, and wings yellowish brown, crossed 

 with black. Rump rufous, with occasional black bars. Primaries dark brown, with broad buff bars on the outer 

 webs. Secondaries buff, barred with brown, and mottled with black. Throat light brown. Breast ashy, barred 

 with black. Flanks rufous, barred with black; abdomen dusky. Tail long; middle feathers brownish white crossed 

 with broad irregular black bars; lateral feathers crossed with yellow, black and chestnut. Bill horn colour; legs 

 and feet brown. 



B. "Female. Top of head and cfest brown, with a black central streak in the feathers. Feathers of the neck 

 and breast dark brown, with white margins. Throat white. Upper part of back rufous, barred with dark brown, 

 and margined with white. Rump reddish brown, mottled with black. Primaries dark brown, barred with buff. 

 Secondaries chestnut, barred with black and buff, and mottled witli black. Flanks and lower part of breast reddish 

 buff. Tail reddish brown, barred with black and buff, and mottled with black. Bill horn colour." 



For selected feathers of female and wing of Juvenal see plate 67. 



EXPLANATION OF PLATE 67. 



Selected feathers from a male Simla horned pheasant, Tragopan melanocephalus. x 1.6. Toda del., 

 Aug. 1904, from a mounted specimen in the Field Museum, Chicago. 



A. A rump-feather; shows that small white spots are parts of discontinuous bars. Passing towards the base of feather 



spots are actually parts of continuous bars. The neat network forming circular or hexagonal figures, 

 inclosing each a spot, are derived from narrow bars that alternate with wider bars, as the feather shows 

 plainly towards base. 



B. From back of neck, lateral, just in front of scapulars. A white spot only a little wider than long, in center of a 



blackish area; elsewhere bars that are wavy or zigzag in form, due to tendency to form narrow bars alter- 

 nating with wider ones. 



C. From the flank at level of leg. The dark center and white center are larger. 



D. An under tail-covert. Dark center scarcely marked by more than a few touches of white bars; white center 



extends nearly across feather, showing more of the bar nature. It may be regarded as a fusion of several 

 bars. These feathers show that dark center is primary, bars and spots secondary, in origin. 



EXPLANATION OF PLATE 68. 



Polypledron bicalcaratum. Toda del., 1904, after Elliot (Monograph of the Phasianidse). 

 The descriptions are those of Elliot: 



A. "Male. Head covered with a lengthened crest, grey and black alternating at the base, and tipped with bluish. 

 Throat covered with brownish-white feathers. Neck and upper part of back brownish white, crossed by narrow lines 

 of blackish brown. Back, wings and tail yellowish brown, spotted with blackish brown, with a luminous spot of 

 brilliant green, surrounded with black near the end of each feather. These spots are very large on the tail feathers, 

 and confined on Hie lateral ones to the outer web. Rump yellowish brown, minutely dotted with blackish brown. 

 Primaries and inner webs of secondaries dark brown, the outer webs of the latter yellowish brown, mottled with 

 dark brown. Entire underparts yellowish brown, minutely mottled with dark brown; the shaft white. Bill, upper 

 mandible blackish brown; under mandible horn colour. Feet and tarsi black. Naked space around the eye red. 



B. "Female. Similar to the male; but the brilliant spots upon the back are black without lustre, and those on 

 the tail, though metallic, are much smaller than those of the male." 



