White-breasted Dippers. 381 



swift-running water. In the mountains the Di^^per usually 

 spends the summer months at considerable altitudes, and only 

 forsakes these, its breeding-haunts, to pass the winter at some 

 lower altitude near the foot of the same mountain- range. Thus, 

 as may be taken for granted, isolation lias caused the group 

 to be split up and subdivided into several '' local forms " or 

 " subspecies,^^ whichever naturalists may choose to term 

 them. These forms have become permanently distinct, though 

 the diflPerences are but slight, and in a large series inter- 

 mediate forms are usually found ; but all the facts point to the 

 various forms having descended from one parent stock. It is 

 not my intention to propound abstruse hypotheses, nor to 

 conjure up a few glacial epochs to account for the distribution 

 of these various forms ; but I will merely state briefly the 

 facts as they have come under my own observation. I may, 

 however, go so far as to say that it appears to me most pro- 

 bable that Cinclus melanogaster (or Cinclus cinclus, as Dr. 

 Sharpe prefers to call this form) is the parent stock from 

 which all the various forms of White-breasted Dipper (in- 

 cluding even Cinclus leucog aster) have descended. 



Cinclus melanogaster is the most boreal of all the group ; 

 for throughout the whole of Scandinavia, and probably also 

 the whole of Northern Russia in Europe, this form alone is 

 found. I have examined numerous specimens from various 

 parts of Scandinavia and one from North Russia (from 

 Mudjuga, 40 miles north of Archangel) . All of these agree 

 very closely inter se. During severe winters, when driven 

 from its usual haunts by stress of weather, this form has 

 been met with, though rarely, on the coasts of England, in 

 Heligoland, on the coasts of Holland and Belgium, and also, 

 as I am informed by Mr. E. Hartert, in Northern Germany. 



Dr. R. Rowdier Sharpe (Cat. B. Brit. Mus. vi. p. 309) 

 calls in question my statement that C. melanogaster has 

 occurred in Ireland, and adds that an examination of the 

 specimens referred to by me shows that the birds so named 

 " are only young birds of the year of the ordinary Cinclus 

 aquaticus after their first moult, at which time they are 

 hardly to be distinguished from Cinclus ci?iclus." To this 



