NUMBER OF GENERATIONS PEE YEAE. 



65 

















































































































































































































































































































































































































































































































































































































































































































































































































































































































































- 







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- 



















































































o 



A 



































































oooooooo»o 



















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OOOOOOMM^fi ^,-v ,-v^ ,^v> /— 



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ocooooocsejww'i'cio'*^'* 









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^1 

















































OOOOON'*'*'*M'<?'*'*mnMWL'3'*HHOO 



A 1 























OOOOOOOOOOOOOO!0U!i0'*nNN^1 , ni0 

 A 1 









































OOOOC<l->*'*<'*iOa5'^I>>'*I>>COCOiOi-lOOOOOOOOOOOOOOOOO 































t- !C CC 00 !>• SI 



1 

























































































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c 



3 C 



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1 































































































26675°— Bull. 110—12- 



