SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 61, NO. 8. PL. 1 







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Fig. 1 



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Fig. 3 



THE THREE TYPES OF BONE STRUCTURE 



Fig. i. — First type as seen in the amphibian, Nyctalus aviator. 

 Fig. 2. — Second type as seen in the turkey. 

 Fig. 3. — Third type as seen in n?an. 



