82 Mr, E. Gil)son on the Orn\tholo(jy uf [Ibis, 



Possibly Pludsoii lias made an involuntary error when 

 he places the number of eggs at four; I have never known 

 the clutch to exceed three. They are large for the 

 size of the bird and obtusely pointed. The ground-colour 

 varies, passing from clay to yellowish and olive, and then 

 to various shades of brown. The markings are just as 

 diflferent in individual clutches, ranging through violaceous 

 and reddish-brown freckles and streaks to spots and blotches 

 of dark ash-colour, brown and dark brown, and finally 

 merging into black. As a rule these markings are fairly 

 well distributed over all the surface, though there is a 

 tendency for them to increase in number and heaviness 

 towards the blunt end. A large series presents a great 

 variety of colouring, but readily falls into a general 

 classification of five or six lyi)es. 



The average measurement is 52x37 mm., the largest 

 clutch being 52 x 38 mm., and the smallest 50 x 36 mm. 



418. Larus cirrhocephalus Vieill. Grey-capped Gull. 



Iris yellow or pale .straw-colour, as distinguished from 

 the brown or dark brown of L. inaculipennis. 



When the mystery of the Grey-capped Gull's breeding- 

 locality is cleared up^ its previous and subsequent movements 

 throughout the year may be more readily followed. At 

 present it would seem as if that secret is locked up in some 

 of the Patagonian lakes, sinrlarly to the description given 

 of the same species in British East Africa {vide ' The Ibis/ 

 vol. iv. p. 194, April 1916). I should much like to 

 see the mystery solved, and the home of this beautiful and 

 interesting Gull fully established. 



In the meantime I am satisfied to accept Claude Grant's 

 dictum as follows : — " The Grey-headed Gull makes its 

 ajjpearance in the Aju district after the breeding-season and 

 remains throughout the winter, consorting with L. maculi- 

 pennis iu flocks of thousands and feeding largely on the 

 carcases of dead stock. It can be picked out from 

 L. mucuHpennis by its larger size and darker colouring, and 

 the call is also louder and harsher.'^ 



