My own researches commenced immediately after passing the Equator, from whence, throughout the entire route to Australia, I omitted no opportunity of studying the habits, and collecting the different species of the oceanic birds that came under my notice: these observations were again resumed on my return to England; and as the outward passage was by the Cape of Good Hope, and the homeward one by Cape Horn, they extended round the globe, and, as will be seen in the course of the work, have led to some important results. And here I must acknowledge my obligations to the various captains with whom I sailed, namely Captain M^cKellar of the “Parsee,” which vessel conveyed me to Van Diemen’s Land; Captain Harding of the “Black Joke,” in which I proceeded from Launceston to Adelaide; Captain Fell of the “Catherine Stewart Forbes,” in which I returned from Adelaide to Hobart Town; Captain Gilchrist of the “Potentate,” in which I sailed from Hobart Town to Sydney; and Lieutenant Mallard, R.N., of the “Kinnear,” which brought me to England; all of whom rendered me every assistance in their power, and the use of a boat and crew whenever the weather would admit of one being lowered, by which means I was enabled to obtain nearly forty species of Petrel, being the finest collection of the _Procellaridæ_ ever brought together. At the commencement of the work it was not expected that it would prove so extensive as it has become, since not more than about 300 species were then known, which number has now been increased, by the united efforts of myself and those who have so kindly aided my views, to upwards of 600 species, among which are comprised many forms remarkable for their novelty, the anomalous character of their structure, and the singularity of their habits, such as the Bower Birds (_Ptilonorhynchi_ and _Chlamyderæ_) and the Mound-raising Birds (_Talegalla_, _Leipoa_ and _Megapodius_). The singular runs or bowers of the _Chlamyderæ_ were considered by some explorers to be the cradles of the infants of the aborigines, and the mounds of the _Megapodius_ to be tumuli, errors which have been rectified in the present work.