59 



[Vol. xxxi. 



and underparts white tinged with buff; thighs dusky ; under 

 wing-coverts and bend of wing washed with pale fawn-colour. 

 Iris brown in the male, red in the female ; bill grey ; feet 

 slate-grey. 



Adult male. Total length about 180 mm. ; culmen from 

 feathers on forehead 16^ ; wing 84 ; tail 77 ; tarsus 32. 



Adult female. Total length about 177 mm. ; culmen 

 from feathers on forehead 15 J; wing 79; tail 74; tarsus 29. 



Another male has a large portion of the plumage 

 showing that curious tendency to albinism which is so 

 often to be found in the allied A. vaughani Sharpe, from 

 the Pitcairn Islands. This individual has the head mostly 

 white, with the exception of a few dark feathers on the 

 forehead and occiput ; feathers of the upperparts and wing- 

 coverts a mixture of brown and white, many of the brown 

 feathers being tipped with whitish, producing a mottled 

 appearance; primary-quills mostly dark brown,! one or two 

 of the middle and inner ones being tipped with white; 

 secondary quills largely white on the left wing, less so on 

 the right ; tail mostly white, some of the middle feathers 

 only being partially brown ; underparts, including the sides 

 of the head, chin, and throat, white. Iris brown ; bill grey ; 

 feet slate-grey. 



Types in the British Museum : $ ? . Nos. 9 & 9 a. 

 Henderson Island, S. Pacific, 27-29. x. 12. D. R. Tait 

 coll. 



Obs. This species differs from A. vaughani in having the 

 feathers of the head uniform brown, not edged with yellowish- 

 white, which gives the crown of that species a somewhat 

 scaled appearance. 



The amount of white in the plumage of Acrocephaline 

 birds from Pitcairn and other Pacific Islands appears 

 to vary greatly in different individuals, and is generally 

 unevenly developed on the two sides of the body. It would 

 seem as though it might be due to degeneration caused by 

 inbreeding. 



