118 



THE WORLD OF LIFE 



The diagram here given is formed from the measurements 

 of six separate portions of twenty male specimens of the Bob- 

 o'-link or Rice-bird (Dolichonyx oryzivorus)^ very common in 

 I^orth America. All were obtained in the same place on the 

 same day, so that there could be no suspicion of their being 



Inches 

 6 i 2 



g JO ]] 22 23 24 25 26 27 28 J9 20 5 



1 2 3 4 5 6 7 3 9 lO 22 22 23 14 J3 16 27 28 29 20 



Rice-hird ( Dolicho2iyX'Oryz2voras .J 30 Males 



Fig. 10, — Diagram of Variation. 



