Valley of Engelberg. 87 



continent, which is as comparatively rare in 

 England as our common Pied Wagtail is abroad. 

 The two forms arc very closely allied, our Pied 

 Wagtail in winter very closely resembling the 

 White bird in its summer dress. The difficulty 

 of distinguishing the two caused me to pay great 

 attention to these White Wagtails whenever I 

 saw them. If you see a bird in summer which 

 has a uniform pearl-gray back, set off sharply 

 against a black head, the black coming no further 

 clown than the nape of the neck, it is the White 

 Wagtail. You must look at his back chiefly ; it 

 is far the most telling character. The male Piecl 

 Wagtail has at this season a black back, and the 

 female has hers darker and less uniform in colour 

 than the genuine White bird. I shall have some- 

 thing more to say of Wagtails in the course of 

 our walk ; but let me take this opportunity of 

 asking the special attention of travellers on the 

 continent to these most beautiful and puzzling 

 birds, whose varieties of plumage at different 

 seasons of the year seem almost endless, and 

 whose classification is still by no means finally 

 settled. 



