INTRODUCTION. 1X 
ferent years), Otis macqueeni (1), Anser ruficollis (12), 
Tadorna rutila (8), Histrionicus torquatus (7 or 8), and 
Somateria stelleri (2). Of these, as might perhaps be ex- 
pected, the majority are small insessorial birds which, 
travelling overland by short stages, would have less difficulty 
in reaching our shores than if they had to contend with the 
winds and storms which sweep a vast expanse of ocean. It 
should, however, be remarked that although a larger number 
of insessorial birds (8) have occurred less frequently, a 
smaller number of natatorial birds (4) have occurred a 
greater number of times. From what we know of the habits 
of these, they would appear to be, with one exception, fresh- 
water species (that is, frequenting inland lakes and estuaries), 
and therefore likely to travel hither by an overland route. 
There is of course a difficulty in relying too strongly upon 
statistics of this kind, from the fact that few species are 
strictly confined to the country which they are said to inhabit. 
In many cases the most that can be said is, that a species is 
more numerous in one particular country than in any other ; 
and this is the test which has been applied in determining 
the habitat of the rare and accidental visitants which are in- 
cluded in Part Il. of this Handbook. Bearing this in 
mind, the classification of a species as Asiatic—for example 
S. stelleri, which is also found, though less frequently, in the 
northern parts of Europe and America (p. 164))—is really less 
arbitrary than at first sight might appear to be the case. 
The species which have visited us from Africa, eleven in 
number, are :—Pycnonotus capensis (1), Aédon galactodes (2), 
Cuculus glandarius (2), Caprimulgus ruficolis (1), Perdix 
petrosa (4 or 5, but doubtfully true immigrants), Cursorius 
gallicus (19), Grus virgo (1), G. pavonina (1), Ardea comata 
(21), A. russata (3), and Plectropterus gambensis (4). Here 
it will be observed the grallatorial birds are in the majority ; 
