72 COMPARISONS OF STBUCTURE IN ANIMALS. 



prey, darting at them as they rose to the 

 surface, and carrying them away. He infers, 

 besides, from the form of the posterior limbs, 

 that they had the power of standing firmly 

 on the ground, where, with their wings closed, 

 they moved about in an iipright attitude, 

 somewhat like birds ; but from the weakness 

 and want of expansion in the haunch-bones, 

 and from the deficiency of robustness in the 

 vertebras of the loins, we doubt this. It is, 

 however, probable, that they could perch on 

 the branches of trees, and scramble up the 

 trunk, or up rocks and cliffs, by means of their 

 fore and hind feet conjointly. 



No reptiles of the present day have the 

 limbs constructed for the purpose of flight. 

 There are, however, certain little lizards be- 

 longing to India and its islands, distinguished 

 by the startling name of dragons {draco) which 

 have a wing-Uke expansion of skin along their 

 side, and which is capable of being furled up, 

 (somewhat in the manner of a fan,) and on 

 the contrary, spread out. This membrane is 

 supported by the false ribs, which are elon- 

 gated, and also movable, at least so far as to 

 fall back or be brought forward at pleasure, 

 but not to be agitated so as ' to beat the air 



