10 
FIRST BOOK. 
4. These wings are very curious, and not at 
all like a bird's wings. They have no feathers, 
but are formed of skin, spread out on a thin 
framework of bone, in something like the way 
silk is spread out on the ribs of an umbrella. 
5. The bat's finger-bones are drawn out to a 
very great length, so that the middle finger is 
Skeleton of Bat. 
sometimes longer than the whole body. The skin 
spreads not only between these long finger-bones, 
but also to the bat's sides, and even between its 
hind legs." 
6. I think the wings must be very large," said 
John. 
''They are," replied his father. ''When a bat 
is not using them it folds them up, as a fan is 
folded, and packs them against its sides. 
7. "Just where the four finger-bones meet, and 
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