''XIV 



Showing the method used by us in measuring the bill from 



its tip to the base of the slcull. One end of tlie dividers is 



pressed along the culmen to the base of the skull, which is 



usually concealed by feathers. 



TJPPER-P.4JRTS. 



Uxder-Parts. 



Outer 



supraarbitaL 





Ventrsl 

 tract 



Crural 

 tract 



Topography of the nestling to show the down-tracts referred to, especially 

 in the descriptions of nestling Passeres. 



