WHITE-WINGED PETREL. 37 
Mathews, from East Australian seas (probably breeding on the New Zealand Sub- 
antarctic Islands) in their slighter bill, and more uniform grey tail and shafts of 
tail-feathers yellowish, not white. 
Genus COOKILARIA. 
Cookilaria Bonaparte, Comptes Rendus Acad. Sci. Paris, Vol. XLIII., p. 994, Nov. 1856. 
Substitute name for ‘“‘ Rhantistes Reichenbach.’’ Type (by original designation): Pro- 
cellaria cookti Gray. 
Rhantisies Reichenbach, Nat. Syst. V6gel, pt. Iv., 1852 (? 1853). Type (by original designa- 
tion): P. cookii Gray. 
Not Kaup, Skizz. Entwick.-Gesch. Nat. Syst., p. 105, 1829, 
Medium delicately-built Petrels with short bills, long wings, medium tail and 
medium legs and feet. 
The bill is comparatively short and generally stout, as in Pterodroma, usually 
a little less than the length of the tarsus ; the variation in bill formation in this 
genus is noteworthy, one form having quite an elongate bill almost equalling the 
tarsus, and with the unguis less strong and hooked than in the other forms. 
The wing is long with the first primary longest, and the tail is wedge shaped, 
much more than one-third the length of the wing and in some cases nearly half the 
length. The legs are slender, not laterally compressed and covered with reticulate 
scaling, the toes fully webbed anteriorly, the hind-toe a simple straight claw. The 
tarsus is about one-third the length of the tail and the legs are typically coloured. 
Coloration bluish-black above, white below. 
This genus is an example of the fatuity of depending upon “ structural ”’ 
characters alone, as these, calculated from the skin, do not take into review the 
trunk features, which are significant. These birds are very different in form, habits, 
ery and colour pattern of downy young from the large Pterodromine species, but in 
structure they differ but little as to proportions of wing, bill, etc. 
¢ 
28. Cookilaria cookii.—WHITE-WINGED PETREL. 
[Procellaria cookii Gray, in Dieffenbach’s Travels in New Zeal., Vol. II., p. 199, 1843, middle 
Jan.: New Zealand. Extra-limital.] 
Gould, Vol. VIL., pl. 51 (pt. xxv.), Dec. Ist, 1846. Mathews, Vol. II., pt. 2, pls. (87) and 88, 
July 31st, 1912. 
Procellaria leucoptera Gould, Ann. Mag. Nat. Hist., Vol. XIII., p. 364, May Ist, 1844: Cabbage 
Tree Island, Port Stephens, New South Wales. 
Rhantistes veloc Bonaparte, Comptes Rendus Acad. Sci. Paris, Vol. XLII., p. 768, May 1856: 
New name for P. leucoptera Gould. 
Cookilaria cookii byroni Mathews, Bull. Brit. Orn. Club, Vol. XXXVL., p. 48, Feb. 3rd, 1916 : 
“ Byron Bay, N.S.W.”’ errore = Cabbage Tree Island, New South Wales. 
DistTRIBUTION.—New South Wales. 
Adult male—Head, hind-neck, sides of neck and mantle black, like the lesser 
wing-coverts, bastard-wing, primary-coverts, outer webs and tips of primaries and 
the long scapulars ; inner webs of primaries brown near the shafts, white on the 
remaining portion of the inner webs; median and greater wing-coverts ash-grey 
as also the back and short scapulars ; innermost primaries and secondaries ashy- 
grey, basal portion of inner webs white; axillaries white; upper tail-coverts and 
tail pale ash-grey, some of the outer feathers minutely mottled with white and grey 
on the inner webs ; feathers of the fore-head black, fringed with white ; lores, chin, 
throat, and entire under-surface white, including the long under tail-coverts, sides 
of body and under wing-coverts ; the small coverts round the margin of the wing 
slate-grey narrowly edged with white ; sides of breast dark slate-grey. Total length 
307 mm.; culmen 25, wing 215, tail 95, tarsus 30. (Taken from the co-type of 
