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THE AMERICAN NATURALIST [Vol. LII 



ER Er = blue cross-over X eR eR = ordinary splashed ; 

 F, ER eR = blue, 



Er eR = blue. 



If blue cross-over of the type ER eR were mated with 

 ordinary black the expectation would be all blues instead 

 of the usual blues and blacks in equal numbers, viz. : 

 ER eR = blue cross-over X Er Er = black; 

 ER Er = blue, 

 eR Er = blue. 



This second type of blue cross-over individual, ER eR, 

 mated with ordinary blue, would give an expectation of 

 3 blues to 1 blue-splashed instead of the ordinary 1:2:1 



ER eR = blue cross-over X Er eR = ordinary blue ; 

 Fj ER Er = blue, 



ER eR = blue, 

 eREr = Mue, 

 eR eR — blue-splashed. 

 If black cross-over Er er were mated with ordinary blue 

 the expectation would be 2 blacks to 1 blue to 1 blue- 

 splashed instead of the ordinary ratio of equal numbers 

 of blues and blacks, viz. : 



Er er = black cross-over X Er eR = ordinary blue ; 

 Fj ErEr = black, 



EreR = blue, 

 erEr = black, 

 er eR = blue- splashed. 

 This same individual Er er (black cross-over) mated 

 with an ordinary splashed bird would give an expectation 

 of half blues and half blue-splashed instead of all blues, 

 as in the case of ordinary black and blue-splashed, viz. : 

 Erer~ black cross-over XeReR = ordinary blue- 

 splashed; 

 F 2 EreR = blue, 



er eR = blue-splashed. 



