504 ORGANS OF FLIGHT :-FLYING FISH, PENGUIN, ETC. 
movement as one of flight, since it does not appear that they 
have any power of propelling themselves in the air; the 
impulse being given at the moment of their quitting the 
water, in the manner of a leap. From 50 to 100 yards, how¬ 
ever, are sometimes traversed by the Fish at one leap; and 
the height to which it rises from 
the surface of the water is occa¬ 
sionally such as to carry it over the 
deck of a ship. On the other hand, 
there are several among the diving 
Birds which use their wings as 
instruments of progression beneath 
the water—in other words, as fins. 
The most remarkably constructed 
of all these is the Penguin (fig. 
246), in which the wings are so 
short as to he incapable of answer¬ 
ing any other purpose; but there 
are several species in which they 
Fig. 246 .—Penguin. may be used as organs of flight 
in the air, without losing their fin-like power in the water.— 
There are several animals that can sustain themselves for a 
short time in the air, by the aid of 
an expanded surface formed by an 
extension of the skin and serving 
as a parachute. This is the case, 
for instance, with the Galeopithecus, 
or Flying Lemur (fig. 247), the 
Flying Squirrel, and the Petaurus, 
or Flying Phalanger (Zool. § 314), 
which have the skin stretched out 
on either side like a cloak, sup¬ 
ported by the anterior and pos¬ 
terior extremities and by the tail. 
By this parachute-like surface they 
are sustained in extensive leaps 
from bough to bough; though it 
does not enable them to support 
themselves in the air for any length 
of time. In the Draco Volans (fig. 248), a little animal which 
lives among the trees of tropical forests, the body is furnished 
