8956 Birds. 
primaries of the willow grouse should be white at all seasons, and that the belly in, 
the summer is always much lighter than the back; in fact, often pure white. I will 
now, however, ask auy one conversant with the habits of the red grouse, whether he 
ever observed one perch in a tree? did he ever find a nest in the forest? or did he 
ever know the red grouse, even accidentally, frequent the small birch, willow, or fir 
forests which lie remote from the moors? In all these particulars the willow grouse 
differs from the red grouse, and in so great a degree that you never, by any chance 
(at least I never did), find the willow grouse on the open moors or fells, never higher 
than the willow and birch bushes afford them a good shelter. And I may notice 
another great difference in the habits of the two birds, I have always, in August and 
September, fouung that the red grouse are partial to dry situations, whereas at this 
season of the year the willow grouse invariably select the moistest places they can 
find —small belts of willow bushes by the sides of forest streams, often on wet wood- 
land mosses or morasses, but never out of covert; and IL consider the name of willow 
grouse most appropriate. I still maintain my original opivion, that although there 
may be a slight resemblance between the willow grouse and red grouse in summer 
plumage (and this resemblance is very slight), here itends. * * * I wish (if we 
are not to consider such striking differenees in the habits of life in two birds of the 
same family as I have just pointed out are not to justify us in considering them as 
two distinct species) some one or other of your more learned readers would tell us in 
plain English what constitutes the difference between a species and a variety. Surely 
it is scarcely consistent for us to set down the willow grouse as nothing but a variety 
of the red grouse, when we retain in our Faunas as distinct species the thrush nightiv- 
gale, the lesser whitethroat, the willow warbler, the pied wagtail, the grayheaded 
yellow wagtail, the tree pipit, the short-toed lark, the firecrested wren, the lesser red- 
pole, the tree sparrow, the parrot crossbill, and some other birds which I could 
mention. In all those which I have named the differences existing between them 
and their nearest relations in the same family are no wore striking than between the 
willow and the red grouse; in fact, in many not nearly so striking, for their habits of 
life are in nearly every case the same, and yet we admit these as undoubted species 
(with, perhaps, the exception of the wagtails), while at the same time we wish to make 
two birds whose habits of life are so totally at variance with each other, as one and the 
same species,” Dr. Bree, in his beautiful work on the ‘ Birds of Europe not observed 
in the British Isles, says, ‘‘ In the present day it is more difficult than ever to define 
the character of species.” Grant says that “ species-mongers” have been destroyed 
for ever by the all-powerful wand of Mr. Darwin. I for one, however, refuse to submit 
to a dogma of this kind, and will take the liberty of considering the Tetrao Saliceti as 
a species perfectly distinct from that of T. scoticus. Its affinities are more with the 
ptarmigan than with the red grouse, but it is distinct from both. Again Mr. Norman 
says (alluding to the eggs of the willow grouse in the possession of Lord Garvegh) 
“perhaps his lordship would allow these tv be examined, and by this means tend to 
clear up this disputed question.” Now, in my bumble opinion, nothing tends to mis- 
lead so much as the eggs of closely allied species; for instance, what would Mr. N. say 
to calling the blackbird (taking that bird as the normal type), the ring ousel, the field- 
fare and the redwing, all Turdus merula? and yet the eggs of these birds assimilate so 
closely that not even our best oologists are able to specifically separate them, when 
any quantity of each species is intermixed. Aud again, who could specifically deter- 
mine Larus fuscus from L. argentatus by examining their eggs? But to come nearer 
