1916] Chandler: Structure of Feathers 359 



and the Pterocles, with the sand-grouse, on the other. The group 

 is characterized by the great reduction of the plumules and the 

 aftershaft. In the Columbae, which are the most specialized, in 

 this regard, the plumules are entirely absent, and the aftershaft 

 is absent or rudimentary. In the Pterocles, the plumules are evenly 

 distributed, and the aftershaft is present, though small. 



a) Columba livia 

 (1) Eemex 



Shaft much deeper than broad at superior umbilicus, for most 

 of length about as broad as wide, with a narrow, median ventral 

 groove, and striations on side, as in Laro-limicolae. Rami narrow, 

 the ventral ridge inconspicuous. Vanules with very closely set bar- 

 bules, the distals 45 per millimeter, the proximals about 35. 



Inner vane. — Distal harbules (pi. 29, fig. 64a) with short wide 

 base, about 0.18 mm. long by 0.037 mm. wide, the ventral teeth 

 very broad and triangular; nuclei in a strikingly diagonal line, 

 even more so than in Galli. Pennulum little if any longer than 

 base ; more or less arched dorsad ; booklets small and slender, 

 usually 6 in number, proximal 3 short, distal 3 progressively in- 

 creasing in length; ventral cilia short, curved, subequal, well sep- 

 arated from each other; dorsal cilia straight, spinelike, shorter 

 than ventral ones, the proximal two not especially modified. Prox- 

 imal harhules (pi. 29, fig. 64&) relatively very short and broad, 

 the base about 0.4 mm. long by 0.056 wide, with nuclei in conspicu- 

 ously diagonal line as in distals. Ventral teeth usually 5, rather 

 narrow and pointed, not elongated, but always evident. Pennulum 

 very slender and filamentous, about half length of base. 



Outer vane.— Distal harhules (pi. 29, fig. 64c) much like those 

 of inner vane, but, as shown by figure, whole barbule arched dorsad, 

 instead of only the pennulum. Pennulum about as long as base, 

 rather broad in lateral view. Hooklets 6 or 7 in number, small 

 and slender. Ventral cilia as in distal barbules of inner vane, but 

 a little shorter, dorsal cilia developed towards tip, but short and 

 spinelike. Proximal barbules on basal portion of barbs similar to 

 those of inner vane, towards tip ventral teeth become separated 

 from one another, increase in number, sometimes to 7 or 8, and 

 assume a stout curved form, intermediate between typical ventral 

 teeth and typical cilia. 



(2) Other Feathers 



In Zenaidura macroura, used as type for description of 'back 

 feathers, latter have distal barbules much like outer vane of remex, 

 and proximals more like inner vane of remex. Distal barbules 

 with short, broad base, broad ventral teeth, and relatively long 

 pennulum, with short, blunt, ventral cilia (pi. 29, fig. 65a). Hook- 

 lets characterized by presence of one or two prongs or horns on 

 their distal side, as shown in the greatly magnified booklet region 

 of a distal barbule from a covert feather of Columha fasciata (pi. 



