MONOGRAPH OF THE PETRELS. 



Sand-Martin or Kingfisher; they were in dry banks and slopes, where the soil was 

 easily penetrable, and terminated in an enlarged chamber, on the floor of which the 

 egg was deposited without any attempt at a nest. Some of the burrows branched 

 from the main tunnel, but were without terminal enlargements, and were not 

 apparently put to any use by the birds. 



Eggs from Kerguelen Island in the British Museum are described by Mr. Oates 

 (Gat. Birds' Eggs Brit. Mus., I., p. 161, 1901) as white, measuring : Axis, 1.3-1.55 

 inch ; diameter, 1.1-1.3. 



As with P. urinatrix, there is considerable difference in the size of individuals 

 of the present species, and in a series of more than twenty specimens, the dimensions 

 are as follows : — Wing, 4.3-5.0 inches ; culmen, 0.55-0.7 ; tarsus, 0.95-1.1 ; middle 

 toe and claw, 1.1-1.35. 



Nestling. Covered with pale silvery-grey down, the under-surface pure white. 



This stage of downy plumage is followed by a second, in which the down 

 continues until the bird is of the size of the adult. This second downy stage is much 

 darker than the first, and is of a dark sooty-grey colour, lighter and more ashy 

 below. On the feathers of the head and back can be seen traces of the silvery down 

 of the former stage, the sooty-grey feathers having a silvery-grey tip attached to the 

 end of the shaft, the dark plumes having pushed the silvery-grey ones out of their 

 original position and taken their place. 



It is interesting to note that in another downy young bird, the wings are nearly 

 full-grown, and the secondaries are edged with white, which may be taken as a sign of 

 an immature bird. 



The nestlings described above are both from the Chatham Islands, collected by 

 Mr. H. H. Travers and lent by the Hon. Walter Rothschild. 



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