200 Mr. 11. Hall on Birds 



"rookery" (in which I had previously -wandered), and they 

 had taken from a portion of it about eight hundred eggs, 

 leaving some two hundred, and giving the birds the oppor- 

 tunity to lay again undisturbed. The measurements of 

 the eggs do not vary much, and one pattern of marking 

 governs the bulk ; in the minority there are differences. I 

 observed : — • 



[a) Whitish ground, purplish spots appearing as if beneath 

 the surface and purplish-red spots just above it; on the 

 surface conspicuous spots and blotches of a chestnut-umber. 



{b) Ground-colour of green, which is rare, the spots being 

 dispersed as in {a). 



(c) Dull rufous ground-colour, with varying spots : this 

 is not so rare as (6). 



{d) Reddish-white ground-colour, which is not uncommon, 

 the spots varying in size and number. 



The following types, attracting the eye at a glance, 

 provided a series of specimens shewing the stages of pigment- 

 influence in passing along the oviduct : — 



(1) Quite white, exceptional. Several years ago I received 

 specimens of this kind from Maiden Island. 



(2) White, with an innermost faint purple layer of spots 

 and blotches. Specimens varying greatly in size. 



(3) Similar to (2), but with a second and stronger layer of 

 spots upon the surface. 



(4) White ground-colour, with purple and chestnut spots, 

 ■which are quite uniform ; few blotches. 



(5) The type described as (a). 



(6) The type described as {b). 



(7, 8, 9) The type described as (c) ; the extent of ground- 

 colour, and therefore of the spots, variable, some lightly, some 

 heavily marked. 



(10) Similar to (c), with few but heavy blotches. 



The second " rookery," at tlie other end of Hat Island, 

 seemed to contain much the same types of eggs, and remained 

 untouched. This is the only one of these islands which the 

 " Sooty " uses for breeding. Each " rookery " contains some 

 two thousand birds. 



