THE GREY-BACKED MOLLYMAWK 



275 



Genus Thalassarche. 



Smaller, with the back dark grey or smoky. Anterior margin 

 of the underside of the wing dark. Southern Ocean. 



Key to the Species, 



1. Larger : wing 22 inches. T. salvini. 

 Smaller : wing 19 to 21 inches. 2 



2. Bill yellow. T. melanophrys. 

 Sides of the bill dark. 3 



3. Lower edge of the bill dark, T. chlororhynchus. 

 Lower edge of the bill yellow. -1 



4. Yellow of upper edge of bill expanded at base. T. bulleri. 

 Yellow of upper edge of bill narrowed at base. T. culminatus- 





Nest of Grey-backed Mollymawk. 



The Grey-backed Mollymawk. ^ 



llialassarche salvini. 



White, with a pale grey head, except the forehead and crown, which 

 are white. A blackish band in front of the eye and extending over it. 

 Back, wings, and tail, as well as the anterior margin of the under surface 

 of the wing, dark greyish brown. Base of the bill, with a narrow baud 

 of black, outside of which is a strip of orange, which does not show on 

 the dried skin. Bill, bluish horn colour; yellow on the upper edge. Legs 

 and feet, bluish white. Length of the wing, 22 inches; of the tarsus, 3.6 

 inches. Egg — 4.25 inches in length. 



In some birds the head is nearly white, and in that case they 

 cannot be distinguished from T. cauta, of Tasmania. The male 

 is rather larger than the female, and has a stouter bill. They feed 

 on fish, barnacles, and other crustaceans. They breed at the 



