45 8 



MANUAL OF ZOOLOGY 



SECT. 



umbilicus (inf. umb.\ into which fits, in the entire Bird, a 

 small conical prolongation of the skin, the feather papilla. 

 A second extremely minute aperture, the superior umbilicus 

 (sup. umb.\ occurs at the junction of the quill with the vane 



FIG. 258. Columba livia. A, proximal portion of a wing-quill or remex. cnl. 

 calamus ; inf. itmb. inferior umbilicus ; rch. rachis ; sup. nmb. superior 

 umbilicus. B, filoplume. C, nestling-down. (C, from Bronn's Thierreich.) 



on the inner or ventral face of the feather, i.e., the face 

 adjacent to the body. 



The vane has a longitudinal axis or rachis (rch.) continuous 

 proximally with the quill, but differing from the latter in 

 being solid. To each side of the rachis is attached a kind 

 of membrane forming the expanded part of the feather and 



