McCOEMICK'S SKUA. 75 



it is in the older birds, both male and female, in the white and weathered phase of 

 plumage, that the golden tips which do not fade show to greater advantage. 



In a young adult the pale straw-coloured tips of the dark neck feathers are hardly 

 visible, and in a bird of the first year there is no sign of them at all (see, for example, 

 Nos. 72 and 77). In No. 82, an adult male, not only is the golden collar a well- 

 marked feature, but there are gold tips to many of the feathers of the head and crown. 



I know of no differences in the colouring of this bird by which the sexes may be 

 distinguished, but there seems to be a fairly constant though slight advantage in point 

 of size in the female over that of the male. 



Wing. Tail. Bill length. Bill width. Tarsus. 



? 16-5 to 15-3 7'3 to 6'3 2'4 to 2'3 1'55 to 1'3 2'5 to 2'3* 

 $ 16-4 to 15-0 7'4 to 6'3 2-4 to 2-2 1-5 to 1-2 2'5 to 2'2 



Individual variations in the measurements taken from birds of the same sex may 

 have a good deal to do with age, but they are considerable. 



The average weight of three adult McCormick's Skuas was 3 Ibs. 



If the eggs of Megalestris maccormicki and antarctica are examined, something of 

 the same difference in size will be noticed that holds between the birds. Thus in 

 twenty-six eggs of maccormicki, not one reached the measurement of a full-sized egg 

 of Megalestris antarctica. 



In four eggs of the latter, taken on the Macquarie Islands, the measurements are as 



follows : 



8-1 X 5-1 7-55 X 5-1* 



7-65 X 5'0 8-1 X 5-4 



while the measurements of eleven eggs of Megalestris maccormicki taken in McMurdo 

 Sound are as follows : 



Those measurements which are underlined are of the more uniformly coloured 

 eggs, with thinner shells and but few spots or blotches. I believe, as I have said above, 

 that they are the result of an effort to replace a stolen egg by a third. 



It is interesting to note in several of the clutches taken from a single nest, that the 

 distinct types mentioned by Dr. Sharpe in the Report on the ' Southern Cross ' collec- 

 tions, were to be found, not sorted one with another, as might have been expected, but 

 so that in the same clutch an egg of the brown type would be found with an egg of the 

 greenish or olive-grey type, showing that examples of each of the various types of egg 

 may be produced by the self-same bird. 



Of the difference between the nestlings of these two species of Antarctic skua, 

 I can judge only by what has been reported of the young of Megalestris antarctica 



* Inches, teste E.B.S. 



