508 SKELETON OF BATS AND PTERODACTYLE. 
elongated in the wading birds, and the four separate toes, by 
the spread of which the body is firmly supported, though 
resting only on two feet. 
Fig. 251.—SkeLeton or Bar. (References as in Fig. 229.) 
669. In the Bat (fig. 251), however, the plan is very dif- 
ferent. We have here no long stiff feathers, by the projection 
of which from the limb itself the surface may be increased to 
almost any extent ; but the wing is formed by an expansion 
Fig. 252.—SkeELETON oF PTERODACTYLE. 
of soft and delicate skin over a framework of bones, whic 
must consequently be made to support it to its very edge. 
