^^l^J Chandler: Structure of Feathers 291 



(1904), only the hypertrophied calami, the scanty-vaned shaft being 

 first formed and then broken off at the superior umbilicus. No special- 

 ized rectrices are to be found. The aftershaft is enormously developed, 

 nearly or quite equalling the main feather plate, a condition found 

 elsewhere only in plumules and in the ear coverts of some birds. 



The plumage of these birds differs widely from that of the 



ostriches and rheas in being very hairlike and harsh to the touch, 



^ a condition brought about by the looseness of the vanes, and the 



stiffening of the rami, coincident with a reduction and loss of the 



barbules. 



a) Dromaeus novae-hollandiae 

 (1) Body Feathers 



Body feathers characterized by great slenderness of form. Feather 

 plate extremely long relative to width ; total length in a typical back 

 feather of both shaft and aftershaft, about 20 to 25 cm. ; width 

 approximately uniform for entire length, less than 1.5 cm. wide ; 

 feather slightly rounded at tip. Aftershaft not appreciably different. 

 Shaft slender, slightly more so in aftershaft, with a broad, shallow, 

 ventral concavity. Rami typically of rather peculiar form, espe- 

 cially towards tip of feathers, where in many feathers the barbules 

 are more and more restricted to basal portion of barbs and 

 finally lost entirely. These naked terminal barbs set as close 

 together as are the middle, barbuliferous ones (about 8 or 9 per 

 centimeter), with rami very deep dorso-ventrally, and sword- 

 shaped, dorsal edge wide and smooth like the upper edge of a 

 sword blade, lower edge thin and sharp, tapering up to meet the 

 upper edge at tip (pi. 14, fig. 4a). Rami of more proximal barbs, 

 bearing barbules, similar but not so wide or so evidently sword- 

 shaped. 



Barhules alike on inner and outer vanes, usually present to tips 

 of barbs on at least two-thirds of feather, and sometimes to tip 

 of feather; about 1 to 1.8 mm. long, very slender, and very numer- 

 ous, set about 30 to 35 per millimeter on both sides. Unlike those 

 of ostriches and rheas, barbules of typical downy type, with narrow, 

 flattened base, and long, filamentous pennulum (pi. 14, fig. 46). 

 Base short, of moderate width, pennulum almost absolutely thread- 

 like, the nodes very inconspicuously marked by minute prongs. All 

 barbules from either aftershaft or main feather plate, and from all 

 feathers examined, similar in form, differing only in size. 



h) Other types. CasvAiriidae 



Though very much like the emus in all the important characters 

 of their epiphyology, cassowaries differ in a few minor details. A 

 much larger proportion of each feather is composed of naked shaft 

 and rami, and the latter are widely separated from each other, not 



