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 i1 



CHAPTER XIII 



I^EFORE the from limbs of any creaTure had be- 

 come adapted to flight through the air. they 

 sen-ed to assist the hind legs in locomotion on 

 tne groimd. and. ages l-iefore this, a many-rayed mem- 

 brane stretched across the primitive fin. aided its owner 

 in cleaving a way through the water. So. like a palimp- 

 sest, if we look l^neath the outer covering of feathers, 

 we see. in the wing oi the modem bird, the three iinirers 

 hdnting oi widely different ancestral habits. 



The general stnicture and appearance oi the bills, the 

 feet, and wings oi various birds is the result oi a function 

 characteristic of each. The bills are used to procure 

 food, the feet to walk or perch, and the wings to propel 

 the bird through the air. But. as we have seen i:. ^ -.en- 

 case of the bill, these organs are put to many other uses 

 besides the one for which they were primarily adapted. 

 This is only what we should expect when vre consider the 

 relative high position which avian intelligence holds, and 

 the remarkable extremes of en\'ironment with which 

 these stnictures — bill. feet, and wings — are brought into 

 close touch. 



Tlie photograph of the young heron's wing shows 



!lo 



