[Case 18. ] 
| Table- 
case. | 
34 BIRD GALLERY. 
(186) and Black Grouse and Willow-Grouse (187) are exhibited, these 
being much rarer than the hybrid with the Capercaillie. 
In the circumpolar Willow-Grouse (LZ. lagopus) (188) and Ptarmigan 
(L. mutus etc.) (181-183) there are three distinct changes of plumage, 
in summer, autumn and winter in both male and female alike, the 
winter plumage being white in all. 
The great peculiarity of the Red Grouse (L. scoticus) (185), and one 
without parallel among birds even of this genus, lies in the fact that 
the changes of plumage in the male and female occur at differenti 
seasons. 
The male has no distinct summer- (nesting-) plumage, but has distinct 
autumn- and winter-plumages, retaining the latter throughout the 
breeding-season. 
The female has a distinct summer- (nesting-) plumage, also a distinct 
autumn-plumage which is retained till the following spring. 
To put it more concisely, both male and female have two distinct moults 
during the year, but in the male they occur in autumn and winter, and 
in the female in summer and autumn, the former having no distinct 
summer-, and the latter no distinct winter-plumage. 
The Red Grouse is generally regarded as merely an insular form of 
the Willow-Grouse, and it might naturally be supposed that as the 
British species does not turn white in winter, such protective plumage 
being unnecessary in the localities it inhabits, the winter-moult had been 
gradually dropped. But as already shown, this is the case with the 
female only, and the male, for some unknown reason, changes the newly 
acquired buff and black autumn-plumage for a winter-garb of chestnut 
and black, which is retained till the following autumn. 
Order IT. PTEROCLETIFORMES. 
Family Prrroctivz. Sanp-Grovse. 
This small order includes only sixteen species, intermediate in their 
affinities between the Pigeons and Game-Birds. The skeleton resembles 
that of the Pigeons in many important points, but the digestive organs 
are like those of the Game-Birds. The bill is very similar in shape to 
that of the latter, but not so strongly developed, while in the outward 
expression, general shape of the body, the soft and easily detached 
plumage, and the long pointed wings, we find a marked resemblance to 
the Pigeons. The feathers of the body are provided with a well- 
developed aftershaft. As might be expected from the shape of the 
wings and the great development of the pectoral muscles which work 
them, all the Sand-Grouse are birds with immense powers of flight, able 
