banks of the Hunter its most favourite food is the larvæ of a species of ant, which it procures by excavating holes in the nests of this insect which are constructed around the boles and dead branches of the _Eucalypti_, and which resemble excrescences of the tree itself. The season of nidification commences in October and lasts till December, the hollow spouts of the gum and boles of the apple trees being generally selected as a receptacle for the eggs, which are four or five in number, perfectly white, one inch and a line in length, and ten lines in diameter. The sexes present no difference either in their size or colouring, and the young are only distinguished by being of a less brilliant hue, and by the wing-coverts and feathers of the breast being edged with brown. Crown of the head, back, and scapularies dull green; wings and tail green, slightly tinged with blue; ear-coverts, and an obscure circle bounding the green of the head, greenish black; rump verditer green; throat white; line from the nostrils over the eye, nuchal band, and all the under surface buff, becoming deeper on the flanks; bill black, the basal portion of the under mandible flesh-white; feet flesh-red, tinged with brown; irides dark brown. The Plate represents an old and a young bird of the natural size. [Illustration: HALCYON PYRRHOPYGIA: _Gould_. _J. & E. Gould del,^t_ _C. Hullmandel Imp._ ] HALCYON PYRRHOPYGIA, _Gould_. Red-backed Halcyon. _Halcyon pyrrhopygia_, Gould in Proc. of Zool. Soc., September 8, 1840. This new Halcyon is an inhabitant of the interior, but over what extent of country it may range is not yet known. The only parts where I observed it was the myall-brushes (_Acacia pendula_) of the Lower Namoi, particularly those growing on the edge of the large plain skirting the Nundawar range of Major Sir Thomas Mitchell. It was usually seen sitting very upright on the dead branches of the myall- and gum-trees, sometimes on those growing out on the hot plains, at others on those close by the river-side. I succeeded in obtaining both old and young birds, which, judging from the size of the latter, I should suppose had left their breeding-place about a month before I arrived in the neighbourhood of the Namoi, in December. I also saw in this district the common or Sacred Halcyon, but in far less abundance than between the ranges and the coast. This latter species may be hereafter found to be more exclusively an inhabitant of the country bordering the sea, while the Red-backed Halcyon may be exclusively a denizen of the distant interior. The unusual colouring of the back at once distinguishes it from all the other members of the genus inhabiting Australia, but in its general economy and mode of living it presents no observable difference.