36 A MANUAL OF THE BIRDS OF AUSTRALIA. 
Genus ZSTRELATA. 
strelaia Bonaparte, Comptes Rendus Acad. Sci. Paris, Vol. XLII., p. 768, May 1856. Type 
(by subsequent designation, Coues, Proc. Acad. Nat. Sci. Philad., p. 137, May 1866) : Pro- 
cellaria hasttata Kuhl. 
There is a series of these Pterodromoid Petrels which do not show any very 
appreciable difference in structure, but which have probably followed a different 
route of development. We are keeping the present name in view in order to incite 
investigation into this matter. 
Large Pterodromine birds with short stout black bills, long wings, long tail 
and stout legs and feet. 
The bill is comparatively short and stout, only about three-fourths the length 
of the tarsus. The details are typically Pterodromine. 
The wing is long with the first primary longest. The tail is long and wedge 
shaped, nearly half the length of the wing, but less than three times the length of 
the tarsus. The legs are stout, not so much lateral compression, and covered as 
usual, with reticulate scaling ; the hind-toe exists only as a projecting point and the 
long toes are fully webbed. 
Coloration mainly white, wings and back dark coloured. 
27. 4strelata lessonii—WHITE-HEADED PETREL. 
[Procellaria lessonit Garnot, Ann. Sci. Nat., Paris, Vol. VII., p. 54, 1826: Falkland Islands 
Seas. Extra-limital.] 
Gould, Vol. VII., pl. 49 (pt. xxxv.), Dec. Ist, 1848. Mathews, Vol. II., pt. 2, pl. 85, July 
3lst, 1912. 
Procellaria leucocephala Forster, Descr. Anim., ed. Licht., p. 206, (pref. Jan. Ist) 1844: 
Australian Seas. 
Not of Kuhl, Beitr. Vergl. Anat., p. 142, 1820, nor Griffith “1829.” 
Procellaria vagabunda Mathews, Birds Austr., Vol. II., pt. 2, p. 155, July 31st, 1912 (ex 
Solander MS.): Bass Straits, Australia. 
Not of Gray, Genera Birds, Vol. III., p. 648, 1844, as synonym of lessonit. 
strelata lessonit australis Mathews, Austral Av. Rec., Vol. III., pt. 3, p. 54, April 7th, 
1916: Sydney, New South Wales. 
DIsTRIBUTION.—Southern Australian Seas. 
Adult male-—General colour above pale grey, including the hind-neck, sides of 
neck, back, seapulars, and tail, darker on the wings and long scapulars ; lesser and 
median wing-coverts blackish like those round the margin of the wing- and primary- 
coverts ; primary-quills blackish, paler on the inner webs ; secondaries slate-grey, 
white at the base; feathers of the back and short scapulars grey with paler grey 
margins ; upper tail-coverts paler grey than the back, margined with white ; middle 
tail-feathers grey, the outer ones white-mottled or dusted with grey ; feathers round 
the eye blackish ; fore-head, lores, and chin white, mottled with grey ; throat and 
remainder of under-surface white ; axillaries ash-grey, white at base and fringed 
with white at the tips; under wing-coverts pale brown with whitish margins ; 
bill black, iris black ; tarsi and base of feet fleshy-white, toes and outer portion 
of webs black. Total length 413 mm. ; culmen 36, wing 314, tail 130, tarsus 48. 
Adult female—Similar to the adult male; wing 308. 
Immature—Similar. 
Nestling —Undescribed. 
Nest.—A large chamber at the end of a burrow. 
Egg.—Clutch, one ; pure white ; axis 72 mm., diameter 51. 
Distribution and forms —Round the Sub-antarctie Circle. Two forms have been 
suggested: A. 1, lessonti (Garnot), from the Falkland Islands seas; A. l. australis 
