1920.] 



Study of Nest line/ Birds. 



87: 



with a thick wad o£ down remaining on the breast when it 

 has entirely disappeared from all the other portions o£ the 

 body. This is doubtless explained by the fact that tlie 

 contour-feathers are rather more precocious on the upper 



Text-figure 17. 



A B 



Pre-pennae from a young' Goslia\vk {Astur pdltnnhdrivs), 

 three-parts grown. 



A. Secondary feather, with pre-penn;^ adliering to tilanientoiis pro- 



longations of the l)arb. This probably illustr.iles llie tliree 

 generations of pUiniage — protoptile, niesoptile, and teleoptile. 



B. Feather from the crown of the same bird, with pre-pennre sessile on 



the extremity. 



parts; the downy tips to the bnvl)s are thrreforc sooner 

 subjected to iibrasion and are conseqncntly moulted first. 



If we cxaniino pariialiy-Hedgcd specimens of some of the 

 Haptorcs, we will Hud that in many cases the distal barbs of 



