As regards area of distribution the most extensive pearl-oyster grounds of the world are situated on the northern and western coasts of Australia. These are located within the jurisdictions of Queensland, Western Australia, and South Australia; and extend in irregular patches from near Cooktown on the northeast almost to Fremantle at the southwest, a distance of nearly 3000 miles. Those in Queensland are commonly known as the Torres Straits fisheries, as they are especially important there; but they extend a considerable distance beyond each end of the strait, and pearling expeditions are made from the limits of the Great Barrier coral reef northward to the vicinity of New Guinea.[248] Those of Western Australia are commonly spoken of as the Northwest fisheries. The fisheries of Queensland and of Western Australia are approximately equal in extent, as regards number of vessels, boats, and men employed, and the quantity and value of the catch, with the advantage slightly in favor of the Northwest fishery in the last four or five years. In 1905, according to the official figures, the Queensland fishery gave employment to 348 vessels and 2850 men, and yielded shell and pearls worth £135,000, which was the smallest output since 1890. The Western Australia fishery, exclusive of Sharks Bay, employed 365 vessels in 1905, and about the same number of men as in Queensland, and yielded £196,000 worth of shell and pearls. The fishery of South Australia employed about 60 vessels and 375 men, and yielded about £25,000 worth of shell and pearls. This makes for the whole of Australia, except Sharks Bay hereinafter noted, a total of 773 vessels, 6075 men, and an output worth £356,000. It should be understood that the South Australia fishery is not prosecuted on the southern coast of the continent, but on the northern coast, in what is known as the Northern Territory of South Australia. Three species of pearl-oysters are found in Australian waters. The largest species, _Margaritifera maxima_, which is by far the most important and widely distributed, occurs to a greater or less extent throughout the whole of this region. This yields the standard motherof-pearl of commerce. Although the pearls which it yields are among the largest and finest in the world, this mollusk is sought more particularly for the shell, the value of which from season to season averages three or four times as much as that of the pearls. Ordinarily this shell is uniformly white over the entire inner surface, and is commonly known locally as “silver lip”; but some “golden-edged” shell occurs on the muddy grounds in narrow passages between the islands on the northwest coast.