In respect to its reproduction it is strictly parasitic, devolving the task of incubation on the smaller birds, many species of which are known to be the foster-parents; among them may be enumerated the various _Melithrepti_, _Ptiloti_, _Maluri_, _Acanthizæ_, &c. After the young has left the nest and attained a considerable size, it is not unusual to see it fed by two or more species at the same time; this I have witnessed with my own eyes; the young Cuckoo, in fact, selects some low dead branch in an open glade of the forest, from which it seldom moves during the day, as a convenient situation for its various foster-parents to supply it with food, for the procuring and supplying of which all the smaller birds appear to have entered into a mutual compact. The specimens of this bird from Western Australia are somewhat smaller, and have the white marks of the tail less distinct than specimens from Van Diemen’s Land, but these differences are too trivial to be regarded as other than mere local variations. When fully adult the plumage is nearly of a uniform brown, with the inner webs of the wing and tail-feathers relieved by bars and markings of white; the immature colouring on the contrary presents a variegated and very diversified character, which, owing to the constant change taking place, cannot be described so as to render it clear to my readers. When the young leaves the nest, the throat, face and shoulders are black, the feathers of the remainder of the body crossed and spotted with buff; the black colouring gradually gives place to the grey of the under surface, while the buffy marks of the upper surface are retained even after the second or third moult; it breeds in this state, and it is doubtful whether in the female it is ever entirely cast off. The stomachs of those dissected were found to be capacious, membranous, and thickly lined with hair. The egg is about seven-eighths of an inch long by five-eighths broad, and is of a cream-colour speckled all over with markings of brown. The adult male has the head, neck and all the under surface brownish grey, with a streak of dark brown down the sides of the neck; all the upper surface olive-brown, becoming much darker on the wings and tail; basal portion of the inner webs of the primaries broadly barred with white; tail-feathers barred on the margins of both webs with white, slightly on the outer and deeply on the inner; all the feathers tipped with white, and with a mark of white on the stem near the tip, this mark being very small on the central tail-feather, and gradually increasing on the lateral feathers until on the outer it forms a band; under-irides very dark brown; eyelash yellow; gape and inside of the mouth rich deep orange; feet olive.