R H. Thomas 279 



pattern, but showed Swinhoe colour, in that many feathers were deeply 

 stained with brown. Amongst the offspring reared from this bird and 

 the Silver $ (F^ " BBBA," eight in number), two birds exhibited new 

 plumage characters, '' mutations," the one a J^ the other a J , these two 

 mutations were mated iiitei' se in their second year, 1911, and bred the 

 F^^ " EBB A " of this series, reproducing amongst these birds, of which 

 ten were reared to the adult stage, replicas of the plumage mutations. 



Two examinations of plumage were made (see Appendices A and B), 

 the first giving detailed descriptions of the hybrid areas observed 

 (Plates XXII— XXVI). 



In the second examination (Appendix B) I sought, not so much to 

 define the details of the plumage patterns, but rather to make it my 

 task to trace their hybrid origin, and in this investigation the immature 

 eight month plumage of the Silver </, a transition stage between the 

 chick and adult plumage, proved of great value for it was found to play 

 a large part in the varied designs of i^2, -^3, and F^^ in some apparently 

 hybrid characters, and where absent in other hybrid characters served to 

 confirm the presence of the Swinhoe characters. It is plain that the 

 factors for this male immature transition plumage were transmitted by 

 the female parent to her female offspring, and it is interesting to note 

 that the characters of the patterns of that plumage show the connection 

 between the Silver and Swinhoe species : for instance, the flank feather 

 pattern of the immature Silver ^ (Plate XXIV, fig. 3 h) is very similar 

 to the breast feather pattern of the Swinhoe $ (Plate XXIV, fig. 2 a, h), 

 though in colouring they differ widely. 



On the wing, tail, breast, and flank of F^, F^, F^ and i^4 $ $ the 

 scapular, interscapular and tail covert patterns of the Silver cT eight 

 month transition plumage can be traced in competition with the breast 

 and flank of the Swinhoe $ . It is remarkable that upon the breast 

 and some anterior scapulars of the Silver J^ transition plumage (Plate 

 XXII, fig. 16 a, b) was found the same delicate grey shade that dis- 

 tinguishes the plumage of F, mutation ? "P" (Plate XXII, fig. 16 c) 

 and her offspring F4, mutation ? " (r " a male factor transmitted by the 

 female parent. 



The following list of areas having hybrid characters in F^, F^, F^, 

 and F^ may be given : — 



Crest (Plate XXII) j Primary and covert 



Breast (Plate XXIV) ^"^ \ Secondary and covert (Plate XXV) 



Flank „ „ (Centrals 



Thigh (Plate XXVI) ^^ \ Laterals (Plate XXIII) 



19—2 



