1916] Chandler: Structure of Feathers 319 



markably short, about half length of base, very broad proximally, 

 and tapering rapidly to tip ; pigment deeper ventral to nuclei than 

 dorsal to them, reverse being more frequently true in other birds. 



Outer vane. — Distal harhules differ only in absence of dorsal 

 cilia, except a few terminal rudimentary ones (pi. 20, fig. 23c). 

 Proximals, unlike those of any birds so far studied except peli- 

 cans, differ only slightly from those of inner vane, being somewhat 

 smaller, their form exactly similar except that ventral teeth are 

 slightly longer, with tendency to become hooklike, but even at tip 

 of barbs not increasing in numbers and forming a series of ventral 

 barbicels. 



(2) other Feathers 



Back feathers have same structure as outer vane of remiges 

 except that small dorsal cilia are sometimes developed on distal 

 barbules near the base of more proximal barbs. In hreast feathers 

 structure not essentially different. Distals (pi. 20, fig. 2dd) more 

 elongate, and dorsal cilia, except at proximal end of pennulum, 

 better developed. Proximal barbules of exactly same type as in 

 remiges, in neither distal nor proximal barbules any tendency what- 

 ever for development of flexules. 



h) Other Types 



Ciconia ciconia has a very similar structure of its feathers. 

 The chief difference is in the relative narrowness of the proximal 

 barbules. 



Leptoptilus duhius has a slight modification of the structure of 

 distal barbules as compared with those of Mycteria. The first two 

 dorsal barbicels of distal barbules of the inner vane (pi. 20, fig. 24a) 

 are stout and spinelike as usual, but are very much closer together 

 and are not followed by a series of less specialized cilia, thus approach- 

 ing more closely to the heron type. On the outer vane the pennulum 

 of distal barbules is relatively short and furnished with an even series 

 of short blunt dorsal cilia (pi. 20, fig. 24&). The under tail cov- 

 erts of Leptoptilus deserve special mention as they are the source 

 of the famous "marabou" feathers of commerce. These feathers 

 are furnished with stiff, heavy shafts, but have the entire feather 

 downy in structure, a condition seldom found in contour feathers, 

 except occasionally on a very weakly developed breast or belly 

 feather. 



In Plegadis guarauna, or scarlet ibis, there is a very striking 

 modification in the distal barbules to deepen the scarlet color-effect 

 (pi. 20, fig. 26a). As will be seen from this figure, both base and 

 pennulum are profoundly transformed, and all the barbicels except 

 the booklets are lost or greatly changed. Both base and pennulum 



