ALLIED PETREL. 
“ ofi-season ” — that is, they do not breed in the same months as the majority 
of the breeding birds, but occupy the same station when some other species of 
Pufjinus have completed their nesting. How far this is a law is not well known, 
but even in the North Atlantic many young are met with in March ! The nearest 
locality to Christmas Island from which recent specimens have been recorded 
would appear to be McKean’s Island, in the Phoenix group. I have not seen 
birds from there, but have examined a series from the Samoan group. Finsch 
and Hartlaub have given very full details of the bird from McKean’s Island 
in comparison with the form inhabiting the Pelew Islands which they associated 
with it. 
There is a fine series from the Pelew Islands in the British Museum and 
the Rothschild Museum, Tring, which show the birds to be quite constant in 
their characters. These birds are generally accepted as typical “ obscurus,^^ 
but, as I shall show later, they cannot be regarded as such. 
From a study of these, I have arrived at the following facts: The birds 
are brown-black, darker in their first plumage and becoming browner by wear- 
ing ; the lores are all dark, while the dark colour extends on to the sides of 
the breast, forming a patch ; the under-side of the primary- quills shows no 
white, being totally smoky-brown ; the under tail-coverts are all smoky-brown. 
The biU is short and stout, averaging 28 mm. in length and 9 in depth ; the 
wing varies from 194 mm. to 207. Specimens from the Caroline Islands agree 
very well with these in all the above characters. 
Samoan birds differ from those from Pelew in having a longer and thinner 
bill, and the lesser under tail-coverts white ; the bill averages 29 mm. in 
length by 7.5 in depth. 
The Phoenix group lie between Samoa and Christmas Island, and Hartlaub 
and Finsch describe their specimen from McKean’s Island as having the wing 
and bill shorter, yet the latter as stout as in the Pelew bird. It would not at 
all agree therefore with the Samoan specimens. At the same time they gave 
their measurements of the type of P. tenebrosus Pelzeln, which may be here 
reproduced : — 
Pelew specimens. Wing 7.2-7.7 in. ; culmen, exp. length, in. ; height 3|-4 in. 
McKean’s Island „ 6.11 „ „ „ 11 „ „ 4 „ 
P. tenebrosus Pelzeln „ 7.6 „ „ „ Ilf „ „ 3| „ 
Hartlaub and Finsch also noticed a single example from Fiji which they 
could not place, but which is obviously related to the preceding, inasmuch as 
they compared it with their P, auduboni, pointing out that it was smaller and 
had “ the under tail-coverts fuliginous-black P This latter character at once 
dissociates it from P. assimilis, where Salvin placed it. 
61 
