PARASITIC WEAVERBIRDS 139 



alternate tufts of barbulcs which fringe its margin. ITeuce also arise the corre- 

 sponding serrations on the margins of the feather. . . . 



It is remarkable that these filaments, though apparently formed for some tem- 

 porary purpose in the development of the feather, should exhibit a structure as 

 highly complex as that of the feather-barbs themselves. I allude to the double 

 row of barbules . . . which fringe the outer margin of the filament; they are not 

 continuous as on the barbs . . . , but in little tufts, alternating with the surfaces 

 of attachment of the barb-tips. . . . These barbules further exhibit those 

 ultimate fringes to which the name barbicds has been given. 



In ordinary feathers, the barbules on the distal side of the barb are, as is well 

 known, furnished with hooked barbicels . . . while those on the proximal side 

 are simple. But it is remarkable, that in these deciduous filaments . . . both series 

 of barbules are furnished with hooked barbicels. The object of these is obviously 

 to embrace the barbules of the feather barbs, during the attachment of the latter 

 to the filament, and as these barbules are attached to both sides of the filament, 

 it is requisite that the filament should be provided with a double series of hooks. 



It would be of interest to learn if some similar typo of growth also 

 operates in the development of the primaries of tlie saw-winged 

 swallows of the genera Stelgidopteryx and Psalidoprocne, but as j^et 

 no information is available. 



There is some difference of opinion among informed taxonomists 

 whether Steganura comprises one or two species. I tentatively con- 

 sider it comprises one species, but discuss this matter, which is of very 

 considerable biological interest, as fully as current data and under- 

 standing permit under the account of the species. 



Paradise Widow Bird 



Steganura paradisaea (Linnaeus) " 

 Plates 4, 10-12, 10 



Although favorite cage birds for a long time and common, wide- 

 ranging, and conspicuous in the fauna of the open country of Africa, 

 the paradise widow birds, unfortunately, are still inadequately under- 

 stood. I treat all recognized fornas of them here as one specific 

 aggregate, but with further data they may prove to bo divisible into 



" Emberiza jparadisnea Linnaeu?, Systema naturae, ed. 10, p. 178, 175S (Africa, restrictdl to .\ngola, 

 Linnaeus). 



State: a, Inner web; b, outer web; c, serrated margin; d, free portion of filament; e, f. 

 portion attached to both webs; h, barbs of outer web recently detached from the iilament 

 and not j'et incorporated into the web; i, membranous sheath surrounding the immature 

 barbs. Fig. 2, part of filament magniiied to show alternating tufts of barbules on 

 each side. Fig. 3, part of filament highly magnified, with portions of barbs attached 

 as in fig. I, f-g: a, Filament barbules forming two series of tufts, both furnished with 

 hooked barbicels; b, feather barbs belonging to the opposite webs of the feather, con- 

 nected at their distal extremities to opposite sides of the filament; c, barbules of the 

 proximal sides of the barb devoid of barbicels, or furnished with only a very few simple 

 ones. 



