Variations of Saxicola monticola. 335 



very young males resemble the females, but pass through 

 continual changes of plumage from the preliminary acqui- 

 sition of white shoulder-patches to the ultimate development 

 of the grey livery of S. leucomelcena. 



From this it would seem certain that S. leucomelcBna is 

 only the grey-headed phase of S. monticola, the intermediate 

 forms [S. leucomelcena-monticola and S. monticola-leucomelana 

 of Seebohm, Cat. B. B. M. v. pp. 379, 380) being merely the 

 transition stages of the one species. There is no doubt as 

 to the proper separation of the sexes in our specimens. 

 Butler on one occasion shot two males in succession paired 

 with the same female S. monticola, the first in the ordinary 

 (^, e. the most commonly observed) plumage, with the ab- 

 domen slightly mixed with white, and, a week later, the 

 second in the grey phase {S. diluta, B. & D.). Both these 

 birds were sexed carefully, and found to be more or less 

 developed for breeding; and we all obtained male birds with 

 varying amounts of grey and white during the breeding- 

 season, never meeting with a female with any abnormal 

 coloration. 



It seems perfectly clear, therefore, from our experience in 

 the field during a ten months^ residence in the neighbour- 

 hood of Newcastle, and after making a special study of these 

 black-and-white Chats, and collecting a large series of spe- 

 cimens, that there is but one form of female bird of this 

 group, and it is to be inferred from this fact that there is 

 only one species of male consorting with it. The males, 

 however, differ so remarkably in plumage, that we think it 

 only natural that some confusion should have arisen, and 

 that in several instances they should hitherto have been 

 regarded as distinct species. 



To elucidate this matter, consequently, we give the fol- 

 lowing list of the phases of plumage of the specimens col- 

 lected, showing the different stages through which the male 

 bird passes : — 



\st stage. Birds of the year in immature plumage, very 

 similar to the females, though perhaps slightly darker. 



'Znd staijc. Shoulders white, though the patch is not so 



