320 THE NESTS AND EGGS OF 



form (varying from a rotund to an oblong oval), and 

 pure white. Some difference of opinion exists as to the 

 correct measurements of the eggs of this Shearwater. 

 I am disposed to accept those given by Sir Walter 

 BuUer in his History of the Birds of New Zealand, 

 as correct, especially as they have been recently con- 

 firmed by Mr. H. O. Forbes, who gives a series of 

 dimensions in the Ibis for 1893, p. 542. The measure- 

 ments given by Saunders in his Manual of British Birds,, 

 and by some other writers, are too small, and must refer 

 to the eggs of other species. Average measurement, 

 31 inches in length, by 2'0 inches in breadth. Incuba- 

 tion is apparently performed by both sexes, but the 

 duration of the period is unknown. 



Diagnostic characters : Our knowledge of the 

 eg-CTs of the Shearwaters is too limited and too uncertain 

 to allow of any characters being given, even if such 

 exist, by which they may be distinguished. Size and 

 locality are of some service, but unless the eggs are 

 thoroughly well identified they are not o^ the slightest 

 scientific value. 



Family PROCELLARIIU.'E. Genus Puffinus. 



DUSKY SHEARWATER. 



Puffinus obscurus {Gmeli^i). 



(British : Very rare abnormal spring migrant.) 



Single Brooded probably. Laying season, December to 

 May, according to latitude. 



Breeding area: Tropic seas. The Dusky Shear- 

 water breeds in Madeira and the Canaries, probably the 



