VERTEBRATA. 347 



which are adapted for flight, the fingers being immense- 

 ly lengthened, and united by a membranous web. The 

 toes, and one or two of the fingers, are armed with hooked 



Fig. 339.— Bat ( VesperUlio). 



nails. The clavicles are remarkably long, and the ster- 

 num is of great strength ; but the whole skeleton is ex- 

 tremely light, though not filled with air, as in Birds. The 

 eyes are small, the ears large, and the sense of touch is 

 very acute. The favorite attitude of a Bat when at rest 

 is that of suspension by the claws, with head downward. 

 They are all nocturnal. 



Fig. 340.— Skeleton of a Bat., 



