Petrels fi'om the North-East Pacific Ocean. 601 



previously for this genus all proved untenable. It differs 

 from the preceding genus in its short tail, though agreeing 

 in its dark coloration throughout. That it should be 

 generically separated rather tiian subgenerically is a point 

 upon which we anticipate criticism, mainly from workers 

 who glance at the small superficial differences, without 

 considering the lessons to be deduced from such small 

 discrepancies. 



We have indicated that Thyellodroma has a distribution 

 confined to the Indo-Pacific Oceans. It is found breeding 

 probably throughout the tropical and temperate Pacific 

 Ocean, north and south of the Equator, and in the Indian 

 Ocean among the Mascarene Islands and West Australia. 



Neonectris breeds in southern-east Australia and south 

 ISIew Zealand, in both cases in more southerly regions than 

 species of Thyellodroma. It occurs abundantly in southern 

 South America, suggesting a southern breeding-place : it 

 has occurred in the north Atlantic as a straggler, and has 

 always been thought to breed only in the southern Hemi- 

 sphere. It ranges along eastern North America, and these 

 birds were also relegated to southern breeding-places. 



Mathews (Birds Austr. vol. ii. 1913, p. 103) was probably 

 the first to suggest that this conclusion was incorrect, as 

 though Stejneger had previously noted that the birds found 

 on the Commander Islands were " probably breeding/^ he 

 laid no stress upon this, and his statement was consequently 

 ignored. 



We now record breeding birds from the north Pacific 

 Ocean, and emphasize the fact that all statements as to 

 northern birds breeding in the south are mere unconfirmed 

 suggestions and with the present knowledge worthless. 



The fact that Neonectris breeds in the north Pacific 

 Ocean and the south Pacific Ocean, while Thyellodroma 

 breeds in the mid-Pacific Ocean, leads us to give generic 

 value to the slight difference which can hardly be superficially 

 observed. Though Thyellodroma and Neonectris are appa- 

 rently so alike, in life they present different appearances. 



