THE BIRDS OF AUSTRALIA. 
grey and the bill black with a yellow streak on the top and with a bright yellow 
edge to the gape which extends right back under the eye. The yellow shows 
conspicuously on the side of the head. It is not thus shown in Gould’s 
coloured figures.” 
In the Trans, Conn. Acad., Vol. IX., p. 440, pi. viii., figs. 1-2, 1895, Verrill 
thus described a bird he received from Gough Island : — 
Sp. Char. Similar in plumage to T. chlororhyncJius, but the lower mandible lacks 
completely the transverse yellow bar at its base, and is entirely black, except at the extreme 
outer end, where it is slightly tipped with light hom-colour. The bright yellow of the 
culmen begins almost at its extreme base, and gradually deepens and brightens into orange 
in the middle, and finally into dull red on the unguis, growing paler towards the tip. Sides 
and back of head pale ash-grey, forehead white. No dark spot behind the eye. Tarsus, 
tail, and two outer toes longer than in T. cJilororhynchus and bill somewhat deeper at the 
base. Wing 19.25, tail 8.25, tarsus 3.05-3.07, culmen 4.40-4.62, middle toe and claw 
4.44-4.49, outer toe and claw 4.32-4.35. 
Verrill gives his reasons for separating this bird, but admits that he had 
not specimens for comparison, but simply depended on literature for his 
knowledge of D. chlororhynchos. His main point of difference was lack of 
the transverse bar at the base of the lower mandible and differences in the 
proportions of tarsus, toes and bill. 
Recently a bird was procured on Gough Island by the Scottish Antarctic 
Expedition, and reported upon by Mr. W. Eagle Clarke {Ihis, 1905, p. 265). 
That author was unable to recognise in it Verrill’ s Th. cximius, though it came 
from the type-locality of that species, and was comparable in detail with 
Th. chlororhynchos. The difficulty was that though it was in the fuU plumage 
of the adult it had a whoUy black bill, and it was supposed that immature 
birds differed in coloration from the adult and that the bill-coloration was 
obtained at the same time as the plumage-changes were taking place. 
In the Monograph of the Petrels this black-billed bird was noted under 
Th. carteri, but the differences between the two specimens pointed out. Mr. 
W. Eagle Clarke has generously allowed me to examine this Gough Island 
specimen, and I conclude that it is the immature of Th. exhnius. It is abnormal 
in that the outer toe on each foot lacks a joint, but I consider this simply an 
individual malformation. In every other detail it agrees with a bird procured 
not far from Gough Island, and which has the bill coloured very similarly to 
Verrill’s specimens ; this apparently lacks the transverse yellow bar at the 
base of the lower mandible, but close examination reveals a half-hidden dull 
red bar which could be easily overlooked. 
Verrill suggested that the Tristan d’Acunha bird, judging from Moseley’s 
description, was certainly D. chlororhynchos, not D. culminata, and that more- 
over it was different from the Gough Island bird. If such were the case, then 
D. chlororhynchos might be applicable to the Tristan d’Acunha bird. In the 
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