• Blue Petrel, Lath. Gen. Syn. iii. pt. 2, p. 415 (1785).

• Procellaria cærulea, Gm. Syst. Nat. i. p. 560 (1788, ex Lath.).

• Pachyptila cærulea, Illiger, Prodr. p. 275 (1811).

• Procellaria similis, Forst. Descr. Anim. p. 59 (1844).

• Procellaria forsteri, Smith, Ill. Zool. S. Afr. pl. 411 (1849).

• Halobæna cærulea, Bonap. C. R. xlii. p. 768 (1856).

• Fulmarus cæruleus, Gray, Hand-l. of B. iii. p. 107 (1871).

• Procellaria cærulea, Buller, Birds of New Zealand, 1st ed. p. 306 (1873).

Ad. suprà clarè cinereus, pileo summo brunnescente lavato: tectricibus alarum minimis et alâ spuriâ brunnescentibus: remigibus extùs brunnescenti-cinereis, intùs albis, secundariis clariùs: cinereis: caudâ obscurè cinereâ albo terminatâ, rectrice extimâ albicante: fronte, loris, supercilio indistincto, facie laterali et corpore subtùs toto albis, pectoris superioris lateribus et hypochondriis imis cinereis: rostro rufescenti-brunneo, culmine et apice saturatioribus: pedibus flavicanti-albidis: iride nigrâ.

Adult. Upper surface pale ashy grey, darker on the scapulars and washed on the crown of the head with brown; the whole of the small wing-coverts as well as the primary coverts greyish brown; forehead, sides of the face, an indistinct line over the eyes, the throat, fore neck, and all the under surface pure white, stained on the sides of the breast and on the lower part of flanks with ashy grey; outer primaries greyish brown, with black shafts, whitish on their inner webs; inner primaries and secondaries dark grey on their outer webs; middle tail-feathers greyish brown, largely tipped with white, the lateral ones uniform dark grey, and the outermost one on each side entirely white. Irides black; bill reddish brown, darker on the ridge and at the tips; legs and feet yellowish white, with brown claws. Length 11·5 inches; wing, from flexure, 8·5; tail 3·5; bill, following curvature of upper mandible 1·3, from gape to extremity of lower mandible 1·4; tarsus 1·2; middle toe and claw 1·6.

Mr. Gould states that he found this species “very abundant off the north-east coast of New Zealand” in May 1840, and that he observed it in every part of the ocean he traversed between the 40th and 55th degrees of south latitude, both in the Atlantic and Pacific. Nevertheless it is a very rare bird in local collections. The Auckland Museum has, for some years past, possessed a specimen, and in 1877 I received one, in very perfect plumage, from Mr. C. H. Robson of Cape Campbell. I have not met with any other examples.

Mr. Layard records that “it is not uncommon along the coast of South Africa, and is occasionally cast ashore after a gale of wind.”

It is readily distinguished by the scapulars being edged and the tail-feathers broadly tipped with white.

Of the egg of this species Mr. Howard Saunders (in his account of the collection brought from Kerguelen Island by the Transit of Venus Expedition) says that the nine or ten specimens varied a good deal in size, the average being 1·9 inch in length by 1·5 inch in breadth; also that the shell has a granulated surface, and is “of the dead white colour characteristic of the birds of this family,” besides having the usual musky smell.