OX MENDELISM IN PHEASANTS. 279 



23. White Collar Mendelising in Hybrid Pheasants. 

 By Rose Haig Thomas, F.L.S., F.Z.S. 



[Received March 22, 1915 : Read April 27, 1915.] 



(Text-figure 1.) 



Index. Page 



Heredity 280 



Variation 231 



Sex 282 



Two or three years ago it occurred to me that an examination 

 made of the relative numbers of dark-necked and ringed male 

 pheasants shot in our coverts would provide some interesting 

 material wherein to trace the working of Mendel's law. The 

 dark-necked pheasant Phasianus colchicus had been the only 

 inhabitant of Britain's forests and woods for centuries; the 

 pheasant is mentioned in Saxon times in a " bill of fare drawn 



up by Harold for the Canons' households a.d. 1059, and 



preserved in a manuscript of the date of circa 1177"': (see 

 Dawkins, ' Ibis,' 1869, p. 358). The first introduction of Phasianus 

 torquatus, the so-called "ringed pheasant," to our woods was 

 towards the latter end of the eighteenth century. This species 

 has a white collar, broken or interrupted on the throat. 



For two seasons a simple reckoning was made of the males 

 shot, and the data collected are remarkable evidence of the 

 continual Mendelising occurring in the collar of the hybrid 

 pheasants of our coverts, absence being the recessive. 



The grading was arranged as follows : — 



Collar absent. Dark-necked Phasianus colchicus type. 



Few tips. From two or three to a dozen feathers with 



very narrow white margin, found beneath ear- 

 coverts. 



Half collar. Collar arrested beneath the ear-coverts. 



Three-quarters Phasianus torquatus type, collar broken at 

 collar. throat. 



Complete ring. Hybrid mutation collar making a complete circle 

 round the throat. 



The dark-necked male pheasant P. colchicus has the whole neck 

 green lustre. 



The hybrid (P. colchicus X P. torquatus) male pheasant has the 

 green lustre on neck above the collar, but a rich bronzed copper 

 beneath the collar. The "complete ring" differs in individuals — 

 it is sometimes broad, sometimes slender, sometimes medium. 



