SEXUAL DIFFERENCES IN WING FEATHERING. 251 



For an adult male 219 mm. 



For a juvenile male ... ... ... 212 „ 



For an adult female ... ... ... 205 „ 



For a juvenile female ... ... ... 205 „ 



The lowest figures obtained for the same quill-feather were : — 



For an adult male 200 mm. 



For a juvenile male ... ... ... 200 „ 



For an adult female ... ... ... 190 „ 



For a juvenile female ... ... ... 192 „ 



It will be noticed from the foregoing figures that, as far as 

 difference of sex is concerned, there is a marked excess of length 

 for this longest of the flight-feathers in both the old and the 

 young individual male birds over the females of from 7 to 

 14 mm. We thus find Dr. Butler's conclusions fully confirmed 

 when confining ourselves to this feather exclusively, but if the 

 same test be applied to a considerable number of individuals we 

 not only get every degree of length possible for this quill 

 amongst the two sexes, but as a matter of fact the same indi- 

 vidual variation manifests itself in all the other flight-feathers. 

 For this longest one, then, we get a range from a maximum 

 of 219 mm. to a minimum of 200 mm. for adult males; the 

 latter being smaller by 5 mm. to female individuals, both old and 

 young, which is that of 205 mm. 



If the relative lengths range for the adult males between 

 219 to 200, for the young males from 212 to 200, they do the 

 same in the case of the females, which for the adults is one of 

 from 205 to 190, and one of 205 to 192 in young females. 



A reproduction of the table of measurements of all the twenty 

 flight-feathers in the wings of these twenty-seven birds would 

 serve no useful purpose, as may be gleaned from the following 

 example, applying to the first specimen composing the list of 

 birds measured : — 



Primaries. 

 X IX VIII VII VI V IV III II I 



mm. 105 176 209 212 210 195 169 159 150 145 



Secondaries, 



I II III IV V VI VII VIII IX X 



140 138 132 128 121 118 112 105 95 70 



2889 



Sum total, 2889. Formula for index, nn / : . = index, 



20 (remiges) 



144*4. s2 



