i9°7- 3*5 



OBSERVATIONS ON THE WEIGHTS OF BIRDS' 



EGGS. 



BY NEVIN H. FOSTER, M.B-O.U. 



Since recording my observations {Irish Naturalist, vol. xi , 

 pp. 237-245, and vol. xii., pp. 295-297), I have been enabled 

 to examine eggs of the following species. All these eggs 

 were fresh except those of which the state of incubation is 

 noted (these I had not an opportunity of examining eggs in a 

 fresh state), and it may be well to state again that I have 

 found that eggs lose about 15 per cent, in weight during the 

 process of incubation. 



Each set is a clutch taken from one nest, and in some cases 

 where there is a variation in size I have given two clutches 

 distinguished by letters a and b. 



Dipper {ductus aquaticus). 



Inch. Inch. Grains. Inch. Inch, Grains. 



1-05 x 74 = 7\h r °4 x 75 = 74i 



i-o2 x 75 = 72$ i'Q4 x 75 = 77i 



1-05 x 73 = 74i 



PrED Wagtail (Mo tactile tugubris). 



Inch. Inch. Grains. 



74 x -56 = 3°i 



75 x '57 = 3°£ 

 72 x '58 == 31 



Yellow Wagtail {Moiacilla Rail). 



