194 BRITISH BIRDS. 



volume 1, page 209, do not hold good. So that it is not 

 possible to say if the specimens most kindly sent by a 

 good many of my correspondents are actually of con- 

 tinental origin or not. Dr. Hartert, to whom I have 

 submitted the specimens, writes me as follows : — ■ 



" In 1894, I gave names to two British races, i.e., the 

 Scottish and the English Crossbills. The former, which 

 has a very high beak, approaching that of L.pityopsittacus, 

 I called Loxia curvirostra scotica, the latter L. curvirostra 

 anglica. About the former there could be no doubt : 

 birds with such bills, and with a length of wing, 

 intermediate between continental L. curvirostra and 

 pityopsittacus , are known only to breed in Scotland. 

 About the English race I have always felt somewhat 

 uneasy, yet, with the large series which I examined at 

 the time, it seemed to be evident that the hundreds of 

 continental birds at my disposal were very often of a 

 bright red, which I never found in any British example. 

 Moreover, the beaks of English birds were never so 

 small as they frequently are on the Continent, and often 

 approached my scotica. On the other hand, birds with 

 equally large bills were found on the Continent, and 

 since 1904 I have seen many more of them. 



" Of course, when I named my anglica I had no 

 evidence that any of the British birds which I had 

 examined were immigrants, but I believed them to be — 

 with one or two exceptions — native English birds. 



" This year it has been proved, that flocks of Crossbills 

 have crossed the sea between Norway and Scotland, and 

 an invasion of Crossbills has been observed throughout 

 Central Europe as far south as Italy., 



" Now, while I decidedly maintain my scotica — which 

 Scotch ornithologists also recognize, Mr. Eagle Clarke, 

 for example, having at once noticed that this year's 

 immigrants were quite different from the native Scotch 

 Crossbills — I am quite willing to give up my anglica." 



As to the cause of the irruption, there seems no 

 evidence as yet upon which to base a conclusion, but it is 

 to be hoped that our fellow-ornithologists on the Continent 

 may discover if, for instance, Crossbills have been 

 unusually prolific this year, and if for some reason the food- 

 supply in their usual haunts subsequently failed. 



H. F. W 



DIMORPHISM IN THE CROSSBILL. 



So far as the material at my immediate command goes, the 

 upper mandible of the Common Crossbill (Loxia curvirostra) 



