9288 Birds. 
the approach of danger, to skulk and hide or run, or if by sudden sur- 
prise startled into flight, to drop again almost directly. 
By a glance at the diagrams I have sent it will readily be perceived 
how much the three specimens resemble one another in their general 
outline, in their narrowness from side to side, and in the depth of their 
keels; also in the form and comparative length and strength of their 
 clavicles, coracoid bones and scapula. This general resemblance is 
due to their general similarity in habits, which necessitates similar pro- 
visions of form, parts and powers. 
It will be observed, however, that the sternum of G. chloropus is 
provided with the shallowest keel of the three, in proportion to its 
greater size. This is doubtless in consequence of the bird possessing 
comparatively limited powers of flight, being less migratory in its 
habits and a more general resident of Britain than any of the others ; 
also because it uses its wings less, and resorts more to swimming and 
diving than the other two members of this family I have already 
named. For the same reason the sternum and clavicles in this species 
are wider from side to side than in any other rail, and the clavicles 
are slightly more arched, after the fashion of most water birds. 
In the cases of G. chloropus and G. pusilla the body of the sternum 
is prolonged from its posterior margin on both sides of the keel, 
forming two distinct ale or wings directed downwards, and in the 
fresh specimen, united to one another and to the posterior margins of 
the base of the keel by a membranous expansion which completes the 
upper and lower surfaces of the sternum unbroken, gives lightness to 
the entire structure, with a greater breadth of expanse for the attach- 
ment of muscles, and a greater resisting surface to the water when’ 
launched upon that element. 
In the case of G. Crex there are no apparently distinct ale, for 
those portions of the sternum which in both the other species are thus 
elongated and distinct, are in this species united and drawn together 
much more closely by a strong but very narrow band of fibrous tissue ; 
thus reducing the narrowness of the body from side to side to a mini- 
mum, which in this species can be accomplished without impairing in 
any way its provisions for obtaining food and safety, as it does not fre- 
quent marsh and water, but the higher meadow lands, whilst it affords 
the bird extraordinary facilities for gliding through the thick and 
tangled herbage. 
The sternum of G. pusilla, whilst it much resembles that of G. Crex 
in most particulars, differs from it in being provided with distinct ale, 
diverging sufficiently to form, when united by a fibrous expansion, 
