1920.] 



Tail-feathers in Bird-of -Paradise. 



721 



arise, is here twice as broad as in the normal case (resp. 5 

 and 10 mm.). The outer thread-feathers (r") therefrom 

 partially cover tlie inner normal rectrices. Only the inner 

 thread-feathers are surrounded by the hornv cover (//) ; the 



Fio. 1. 



FiCx. 2. 



%/ 



JlCf. 



Insertion of the tail-feathers in a normal case (somewhat 

 diagrammatic). 



r, normal tail-feathers ; r', thread-feathers ; J:, knob from 

 which thread-feathers arise ; h, hornj^ cover of thread- 

 feathers. 



Insertion in the abnormal case. 



?•', normal thread-feathers; r", supernumerary ones; k' , 

 enlarg'ed knob. 



shafts of the outer ones are less white, and nearer to their 

 base they are provided with small webs. The outer two thread- 

 feathers are a little shorter than normal (viz. 48 cm.)^ the 

 inner ones are of normal length (50 cm.). It therefore 

 seems clear that the outer are to be looked upon as the 

 supernumerary ones. 



Dr. Van Oort was so kind ns to show me the Ley den 

 specimen mentioned above. Here there was only one super- 

 numerary feather, and this seemed to arise out of the same 



