FRILLS AND FUNDAMENTAL BARS AS PLUMAGE CHARACTERS. 141 



feather structure in that the tips are raised, or slightly recurved. An early stage 

 of such "frilled" feathers is shown in plate 69, figure E, the bird there shown being 

 an owl-rock hybrid of rather pale coloration and with wing-bars somewhat reduced. 

 This bird illustrates the fact that the frills may appear in the coverts while the 

 primaries remain free of flutes, 



COMMON PIGEON (MONDAIN) AND GUINEA-PIGEON (COLUMBA GUINEA). 



A male common pigeon obtained from a dealer was found to have fluted feathers. 

 This bird was of medium size and with nearly all the primaries of white color. The 

 ground-color of the coverts was nearly black, with gray triangular spots at tips of 

 feathers (pi. 70, fig. A) ; these were remarkably similar to those seen in a C. guinea 

 with fluted primaries, with which the common pigeon is compared. A large white 

 patch was present on the upper part of the breast; the rump was white, and the tail 

 was of the usual dark color. 



This bird shows us an early stage in the development of frills or curls in three 

 of the upper long coverts. The secondaries in the folded wing show plainly a wavy 

 undulating appearance in the lower web, there being from 3 to 5 of these folds or 

 flutes in the apical inch of each feather. The tertials show only 1 or 2 such folds, 

 and these are not so deep. The fourteenth, fifteenth, and sixteenth long coverts 

 show the same feature at the tip of the feather, where the fold in 14 is about 2 mm. 

 high and 2 mm. wide, showing a rather regular dome-shaped outline when seen 

 from behind. In 15 the fold is nearly twice as high, with the sides pinched up close 

 and a slight twist at the summit, thus presenting a quite different figure or structure. 

 In 16 we have a much broader elevation and a trifle less height than in 15, which 

 thus presents still a different figure. In 17 there is no elevation. 



In the primaries, where the lower web is narrower and stiffer than in the upper, 

 we see only faint traces of undulations in the lower web, but quite strongly marked 

 ones in the upper webs, in the terminal portions. The details of the modification 

 on the several primaries, as these are recorded in the legend of the figure (pi. 70, 

 fig. A), show that the longer feathers have the stronger fluting. 



In the Guinea-pigeon the upper (inner) webs of the primaries seem to be longer 

 than the lower, and are folded alternately in and out, or fluted sinuous, so to speak 

 (pi. 70, fig. B). Seen from above, the upper edge takes the form of an undulating 

 line (pi. 69, figs. A and B). The fluting extends over the distal third or less. In the 

 illustration this is shown to be less emphasized than in the common pigeon; in the 

 latter the flutes are a little deeper and more extended on the feather. This fluting 

 occurs just where the feather is most strongly bent in flight, and evidently permits 

 of considerable upward and downward movement without causing any break in 

 the web between the veins. 4 



FLUTES PASS INTO FRILLS. 



The common pigeon described above exhibited a tendency to the peculiar twisted 

 and recurved condition seen in the race of frill-back pigeons, in the upper second- 

 aries, tertiaries, and in a few of the posterior scapulars; in addition to these, about 

 three of the upper long coverts were also affected. This twisting occurred near or 



4 I notice a similar folding in the primaries of a Catenas nicobarica; in one of several Turtur chincnsis the fluting 

 is quite marked; while in the others it is scarcely to be recognized, or is quite absent; in a green-winged pigeon, in 

 hybrids between domestic pigeons and Japanese turtles, and between Zenaidura and the blond ring-dove ; in fact, it 

 has been quite generally observed in certain individuals of both wild and domestic pigeons. 



