1916] Chandler: Structure of Feathers 351 



tiation between base and pennulum, no ventral barbicels whatever, 

 and a series of very highly developed flexules and dorsal cilia, in 

 a continuous series after the booklets are lost. Plate 26, figures 

 52e and / shows the tardiness of the booklet cells to develop any 

 dorsal cilia. Plate 26, figures 52g and h show the method of trans- 

 formation of the proximal barbules, the distals and proximals being 

 exactly the same on the distal half of the barbs. 



In the Aramidae, as typified by Aramus giganteus, the barbules 

 of the dack feathers closely resemble those of the back feathers of 

 the Coraciidae and Megapodidae in that in the distal barbules of 

 the undisturbed vanules the bases are twisted in such a way that 

 although at the junction with the ramus they stand in a vertical 

 plane, they lie in a horizontal plane for most of their length. The 

 distals also resemble somewhat the "peristeropode" Galli in the 

 curved form of the ventral cilia (compare plate 26, figure 51a, with 

 plate 24, figures 45a and 46a). The proximals (pi. 26, fig. 515) 

 also approach the condition in these birds in their elongate taper- 

 ing bases, and very short pennula. The breast feathers have bar- 

 bules which resemble those of rails in the great development of the 

 dorsal series of barbicels, consisting of both flexules and dorsal 

 cilia, but are a little closer to those of the cranes in that they are 

 elongate, and possess a highly developed series of ventral as well 

 as dorsal cilia (pi. 26, fig. 51e). Plate 26, figures 51c and d show 

 the distal and proximal barbules respectively at the base of a barb 

 of a breast feather, showing the method of development of the 

 peculiar type shown in figure 51e of the same plate. 



In Otis tarda, representing the Otididae, the remiges are char- 

 acterized by the remarkable width of the pithy part of the ramus. 

 On the inner vane, on barbs not over about 6 cm. long, the ramus, 

 near its base, is about 1.5 mm. wide, of which the ventral ridge 

 forms a very narrow edge, being less than 0.05 mm. wide. The 

 distal barbules of the remiges are peculiar in their being relatively 

 short, with stout bases and very large, lobate ventral teeth, and 

 exceedingly long booklets, usually seven in number. They are 

 devoid of conspicuous basal dorsal cilia even on the inner vane. 

 The proximal barbules (pi. 27, fig. 535) have a relatively large 

 base, with a rather stout, moderately long pennulum. The back 

 feathers are distinctly like those of galline birds in the structure 

 of their barbules, the distals having both base and pennulum shaped 

 as in the back feathers of Gallus, and the nuclei distinct in the 



