532 APPENDIX. 



H. The Outer Covering {Indumentum). 



142. Outer covering (Indumentum ; Ptilosis). The exterior of the bird in detail. 



143. Feathers (I'liimcv). Composed of ihe stem and the webs. 



144. Stem (.St'(i/>u.'i). The entire central axis oi ihn fuatlier. 



145. Quill {Culamus). The hollow homy liasnl jiortion of the feather. 



146. Shaft {niiachis). The solid terminal portion of the stem in which the fibrrs 



are implunled. 



147. Webs (Ptyonia). The series of fibres implanted on cnch side the shaft, generally 



stiff, and having little 



148. Hooks or barbules along the edges, by which adjacent ones interlock ; somctiiiu's 



so.'t, with the barbules not interlocking, the barbules sometimes wonting. The 



149. Inner ^reb (Pogonium intirnum) is situated on Ihe inner side of the shaft ; the 



150. Outer (externum), on the outer side. 



131. Vane ( Vexillum). The shaft and webs lakcn together, or the portion of the fcatlier 



left when the barrel or quill is cut away. 



