THE ELIMINATION OF THE UNFIT. 215 



The bird (No. 55) whose head was longest (measured from 

 the tip of the beak to the occiput) suffered elimination. The 

 extreme variant in the opposite direction (No. 9) survived. 



The honors for the longest humerus, .780 mm., are divided, 

 Nos. 6 and 44. The bird with the shortest humerus, No. 21, 

 perished. 



The longest femur was possessed by bird No. 55, the shortest 

 by No. 51. 



The surviving birds represent both extremes of variation of 

 the tibio-tarsus (Nos. 18 and 41). In respect to all other col- 

 umns of measurements the survivors possess exclusively never 

 more than one of the extreme forms. 



Both extremes of variation in width of cranium (Nos. 55 

 and 52) are found among the eliminated birds. 



The longest sternum is found in one of the surviving birds 

 (No. 15), and it will be remembered that a long sternum was 

 considered a mark of excellence. The shortest sternum (No. 52) 

 is found among the eliminated birds where the standard is low. 



These extremes of variation are represented on Table IV, 

 and by counting the dark numbers we find that eleven extreme 

 positions (maximum or minimum) are occupied exclusively by 

 the birds which perished, whereas the light numbers show that 

 only five extreme positions are occupied by those which sur- 

 vived. In two cases (the minimum weight and the maximum 

 length of humerus) the extreme positions are occupied alike 

 by birds of both groups, and consequently I have left the 

 spaces blank. In three cases two birds of the same group 

 occupy the same extreme position, but the table is designed to 

 indicate only the extreme positions and not the number of birds 

 occupying them. The number of birds occupying these extreme 

 positions is represented on the previous tables by the exponent 

 I, and if we count up these exponents, we shall find that among 

 the surviving birds there are nine cases of this extreme type, 

 whereas among the birds which perished there are fourteen 

 cases. These numbers are the more impressive when one con- 

 siders that, inasmuch as there are seventy-two of the former 

 birds and only sixty-four of the latter, the chances for the 

 occurrence of extreme variation are not equal in the two groups. 



