LOCOMOTION. 257 
greatly more active than the very small black. ant 
(Ponera contracta, LaTREILLe). 
_ There cannot, however, be a doubt that the wren 
and the tomtit are more active and restless than 
the bustard, the ostrich, or even the eagle; and the 
activity moreover of such small birds is not, like 
that of the gnat, confined to an hour or two, but 
continues almost uninterruptedly during sunlight, 
sleep being, it would appear, less necessary than it 
is to larger animals to restore vigour after exertions 
so long continued. Motion of some kind indeed 
seems as indispensable to life as food and air; and 
even the motions of animals, which may be pri- 
marily accounted for by referring to their exertions 
to procure subsistence, and shelter, and the like, 
must always, in a secondary point of view, give 
them beneficial exercise. 
“All living creatures,” says Pliny, ‘“‘ have one 
certaine manner of marching and going, according 
to their several kinds, unto which they keep, and 
alter not. Birds only vary their course, whether . 
they go upon the ground or flie in the aire. Some 
walke their stations, as crows and choughs; others 
hop and skip, as sparrows and ousels: some run, as 
partridges, weodcocks, and snipes; others again 
cast out their feet before them, staulk and jet as 
they go, as sterks and cranes.”* 
There is a British bird, the swift (Cypselus mura- 
rius, '[emMMinck), which has, at least in name (Apus, 
Beton; Hirundo Apus, Linnaus), been represented 
as destitute of feet; but though its legs are exceed- 
ingly short, the structure of its feet is admirably 
adapted to its economy. The shortness of the legs 
and the great length of the wings render it very 
difficult, if not impossible, for it to rise from an 
even surface, and, as if conscious of this inability, 
if is never seen to light on the ground; “ but,” as: 
* Holland’s Plinie, x., 38, 
Y2 
