754 OAPT. F. W. HUTXON ON A COLLECTION OP [DeC. 5, 



about among the trees above bis head. The true Mutton-bird had 

 not yet commenced to lay. Mr. Cheeseman also informs me that 

 none of the young birds were dark-coloured, but closely resembled 

 the old ones in plumage. Mr. Bell says that the winter Mutton- 

 bird breeds from May to September and that its egg is rather 

 larger and rounder than that of the true Kermadec Mutton-bird. 



As all the specimens sent to me were labelled Sunday Island, 

 the species must occur there too, and some of them may breed later 

 with the next variety, which is the summer Mutton-bird. Indeed 

 this must be the case if the nestling just described really belongs 

 to CE. neglecta. 



CEsTEELATA NEGLECTA, variety. 



One adult from Sunday Island, August 1888. Length 15'5 

 inches, wing 11"25, tail 4*5, bill 1'2, tarsus 1*5, mid toe l-S. 



The whole of the head, neck, breast, and flanks brownish grey ; 

 darker on the back, wings, and tail. Abdomen and crissum white. 

 Under wing-coverts brownish grey. Bill, legs, and feet as in 

 ffi. negUcta. The wings when folded extend about an inch beyond 

 the tail. 



This variety is very closely alHed to the typical CE. neglecta ; 

 but, in addition to the colours, it may be distinguished from it by 

 the contour of the line of junction of the feathers with the base of 

 the bill, which runs from the base of the nasal tubes obUquely 

 backward to the gape, and does not descend as in the typical 

 (E. neglecta. If this character is constant there can be no hesitation 

 in admitting it as an incipient species ; but, unfortunately, I have 

 only one specimen. 



This variety appears to be the true Mutton-bird of the settlers, 

 which is said " to arrive in immense numbers at the end of August 

 or early in September, and to breed all over the main island, but 

 most abundantly towards the tops of the hiUs. Unlike most o£ 

 the other Petrels it makes no burrow, but lays its single egg in a 

 hollow at the root of a tree or even anywhere on the bare ground" 

 (Cheeseman). However, it would seem, as already mentioned, that 

 some individuals of the typical form also breed on the main island 

 in September with the variety, for Mr. Bell sent skins of both 

 kinds to Mr. Cheeseman, who understood him to say that both 

 belonged to the summer Mutton-birds ; but as he also sent at the 

 same time specimens of CE. pliilUpi, there is considerable doubt 

 as to what he meant. Mr. Cheeseman himself says, " I iiud but 

 little difference between the two kinds (winter and summer Mutton- 

 birds), save that this (winter Mutton-bird) has a more distinct dark 

 band across the breast." 



It seems probable that we have here a very mteresting example 

 of the evolution of a new species by isolation due to an alteration 

 in the time of breeding of certain individuals of CE. neglecta. This 

 seems to be a better explanation of the facts, as they are at present 

 known, than the supposition that we Iiave here merely individual 



