£2 



described by the owner. The charge of these was undertaken 

 by Mr. W. W. Mitchell, the Secretary of the Microscopical 

 Section. 



Light refreshments were supplied in the Banqueting Eoom. 

 About 300 persons attended. 



WEDNESDAY, MAKCH 14th, 1894. 



VARIATION IN THE PLUMAGE OF BIRDS, 



BY 



MR. ARTHUR F. GRIFFITH, JNI.A. 



Mr. Grifl&th pointed out that variation in the plumage of 

 birds might be classed as either normal or abnormal, examples 

 of the latter class being also frequently known as " sports." 



Normal variation usually proceeds along one of four lines, 

 and depends on either 



1. Age, 



2. Sex, 



3. Season ; or 



4. Locality. 



1 . The variation depending on age was exemplified by the 

 Greater black-backed gull, the young of which is greyish white, 

 spotted over with grey spots (which vary considerably in size and 

 shape in individual specimens, though their general effect is much 

 the same in all specimens), the adult bird being strikingly white 

 underneath, and of a dark French grey on the back. 



The speckled plumage of the young robin showing no red 

 breast, was also referred to. 



2. To show differences of plumage presented by the different 

 sexes, Hen-harriers and capercaillie were exhibited. In the former, 

 the adult males are clear slatey-grey, while the hen birds are 



