6*) 
396 MOTACILLID A. 
In a paper by Mr. Gould, published in the Magazine of 
Natural History, in the volume for the year 1837, page 
459, entitled “Observations on some Species of the Genus 
Motacilla,” the following paragraphs occur: ‘“‘ While en- 
gaged upon this tribe of birds during the course of my 
work on the Birds of Europe, I was equally surprised to 
find that the sprightly and Pied Wagtail, so abundant in 
our islands at all seasons, could not be referred to any 
described species; and that it was equally as limited in 
its habitat; for, besides the British islands, Norway and 
Sweden are the only parts of EHurope whence I have been 
able to procure examples identical with our bird, whose 
place in the temperate portions of Europe is supplied by 
a nearly allied, but distinct species, the true M. alba of 
Linneus ; which, although abundant in France, particu- 
larly in the neighbourhood of Calais, has never yet been 
discovered on the opposite shores of Kent, or in any part 
of England. As, therefore, our bird, which has always 
been considered as identical with the J/. alba, proves to 
be a distinct species, I have named it after my friend W. 
Yarrell, Esq. as a just tribute to his varied acquirements 
as a naturalist.” 
“The characters by which these two species may be 
readily distinguished are as follows. The Pied Wagtail 
of England, M7. Yarrellii, is somewhat more robust in 
form, and, in its full summer dress, has the whole of the 
head, chest, and back of a full deep jet black; while in 
the White Wagtail, 17. alba, at the same period, the 
throat and part of the head alone are of this colour, the 
back, and the rest of the upper surface, being of a light 
ash-orey. In winter the two species more nearly assimi- 
late in their colouring; and this circumstance has, doubt- 
less, been the cause of their being hitherto considered as 
