Two nests, taken in November on a small island in Coral Bay, near the entrance of the harbour at Port Essington, were compactly formed of dried wiry grass and the fine plants growing on the beach; they were placed in a fork of a slender mangrove-tree within fifteen feet of the water, in which they were growing; but like several other Australian birds, the _Artamus leucopygialis_ often avails itself of the deserted nests of other species instead of building one of its own. Most of those I found breeding on the Mokai had possessed themselves of the forsaken nest of the _Grallina Melanoleuca_, which they had rendered warm and of the proper size by slightly lining it with grasses, fibrous roots, and the narrow leaves of the _Eucalypti_. The eggs are generally three in number, are much lighter in colour, and more minutely spotted than those of any other species of the genus I have seen; their ground-colour is flesh-white, finely freckled and spotted with faint markings of reddish brown and grey, in some instances forming a zone at the larger end: their medium length is ten lines, and breadth seven lines and a half. The sexes are only to be distinguished by dissection, and may be described thus: head, throat and back sooty grey; primaries and tail brownish black washed with grey; chest, all the under surface and rump pure white; irides brown; bill light bluish grey at the base, black at the tip; legs and feet mealy greenish grey. The Plate represents a male, a female, two young ones and a nest of the natural size. [Illustration: DICÆUM HIRUNDINACEUM. _J. & E. Gould del et lith._ _C. Hullmandel Imp._ ] DICÆUM HIRUNDINACEUM. Swallow Dicæum. _Sylvia hirundinacea_, Shaw, Nat. Misc., vol. iv. pl. 114.—Lath. Ind. Orn. Supp., p. lv. _Swallow Warbler_, Lath. Gen. Syn. Supp., vol. ii. p. 250.—Shaw, Gen. Zool., vol. x. p. 613. _Pipra Desmaretii_, Leach, Zool. Misc., vol. i. p. 94. pl. 41. _Crimson-throated Honey-sucker_, Lewin, Birds of New Holl., pl. 7. _Desmaretian Manakin_, Shaw, Gen. Zool., vol. x. p. 18.—Lath. Gen. Hist., vol. vii. p. 240. _Dicæum atrogaster_, Less. Traité d’Orn., p. 303. _Moo-ne-jë-tang_, Aborigines of the lowland districts of Western Australia. By far the greater number of the colonists of Australia are, I am sure, totally unacquainted with this beautiful little bird, yet there is scarcely an estate in either of the colonies in which it may not be found as a permanent resident or an occasional visitor: a closer examination of the birds, and other natural objects with which we are most nearly surrounded, would at all times repay with interest the trouble of their investigation.