I’TEIIODACTYLE. 
231 
cire calculated for progression on the ground, or 
in the water. 
If we compare the foot of the Pterodactyle 
with that of the Bat, (see PI. 22, k,) we shall 
find that the Bat, like most other mammalia, 
has three joints in every toe, excepting the first, 
which has only two ; still these two, in the Bat, 
are equal in length to the three hones of the 
other toes, so that the five claws of its foot range 
in one strait line, forming altogether the com- 
pound hook, by which the animal suspends itself 
in caves, with its head downwards, during its 
long periods of hybernation ; the weight of its 
body being, by this contrivance, equally divided 
between each of the ten toes. The unequal 
length of the toes of the Pterodactyle must have 
rendered it almost impossible for its claws to 
range uniformly in line, like those of the Bat, 
and as no single claw could have supported for 
a long time the weight of the whole body, we 
may infer that the Pterodactyles did not suspend 
themselves after the manner of the Bats. The 
size and form of the foot, and also of the leg 
and thigh, show that they had the power of 
standing fii-mly on the ground, where, with 
their wdngs folded, they possibly moved after 
the manner of birds; they could also perch 
on trees, and climb on rocks and cliffs, with 
their hind and fore feet conjointly, like Bats 
and Lizards. 
