iv 
Doctors are not agreed, as will be seen when their 
judgments pass in review. Sometimes a single occurrence 
is sufficient ; sometimes that is sufficient if it be a Pale- 
arctic bird; but the single American visitant is rejected. 
Sometimes fwo occurrences admit the bird, whilst one of 
our best Authorities once went so far as to say that no 
bird should be considered British that did not breed in 
the land. 
Mr. Dresser says in his article on the Black-billed 
Cuckoo: 
“Tf there 1s no doubt that a species has been obtained 
on one or two occasions, and their 1s no probability of its 
being one escaped from confinement, and also if its range 1s 
such as to admit of its having been driven by stress of 
weather, or straggled to the locahty where it has been 
obtained, tt 1s better to include and figure it than to pass it 
over in silence.’ And this because there may have been 
others unrecorded, and it tends to keep Naturalists on 
the look ont for the species. 
This mention of the range, and the effect of storm 
and wind upon the birds movements, when taken with Mr. 
Baird’s opinion, should certainly dispose of the exception 
taken to American species: in this gentleman’s opinion 
the occurrence, out of all proportion, of American birds 
in Britain, compared with their record on the Continent of 
Europe, not even excepting Heligoland, is due to the 
prevalence of Westerly gales on the Eastern coast, especi- 
ally at the period of the Autumnal Migration; ‘when 
they follow its coasts, or cross tts curves, often ata con- 
siderable distance from land, or ata great height above it 
and are carried away to sea, mainly about latitude 45°, the 
line of the greatest intensity of winds, the first land they can 
make 1s Lingland, whence the fact that most of the species 
have occurred on the British Islands, as well as Heligo- 
