A white siliceous clay, supposed to be from a "Deep Lead," in the Norseman district in Western Australia, has proved to consist almost entirely of siliceous sponge-spicules, belonging to the Monactinellid, the Tetractinellid, the Lithistid, and the Hexactinellid groups (Fig. 69 A, B). The reference of the deposit to a "deep lead" or alluvial deposit presents a difficulty, since these sponge-spicules represent moderately deep water marine forms. This deposit resembles in some respects the spicule-bearing rock of Oamaru, New Zealand, which is of Miocene age. [Illustration: =Fig. 68.--CAINOZOIC SPONGES.= A--Latrunculia sp. (after Hinde). Cainozoic. Deep Lead, Norseman, W.A. B--Geodia sp. (after Hinde). Cainozoic. Deep Lead, Norseman, W.A. C--Ecionema newberyi. McCoy sp. Cainozoic. Boggy Creek, Gippsland, Vict. D--Plectroninia halli, Hinde. Cainozoic (Janjukian). Moorabool, Vict. E--Tretocalia pezica, Hinde. Cainozoic. Flinders, Vict. ] [Illustration: =Fig. 69.--SILURIAN CORALS.= A--Cyathophyllum approximans, Chapm. Silurian (Yer.). Gippsland, Vict. B--Favosites grandipora, Eth. fil. Silurian (Yer.). Lilydale, Vict. C--Favosites grandipora, vertical section. Ditto. D--F. grandipora, transverse section. Ditto. E--Pleurodictyum megastomum, Dun. Lilydale, Vict. F--Halysites peristephesicus, Eth. fil. Silurian. N.S. Wales. G--Heliolites interstincta, Wahl sp Vict. (transv. sect). Silurian.. ] In the Cainozoic beds of southern Australia Sponges with calcareous skeletons are not at all uncommon. The majority of these belong to the Lithonine section of the Calcispongiae, in which the spicules are regular, and not fixed together. Living examples of these sponges, closely related to the fossils, have been dredged from the Japanese Sea. The fossils are found mainly in the Janjukian, at Curlewis, in the Moorabool River limestones, and in the polyzoal rock of Flinders, all in Victoria. They belong to the genera _Bactronella_, _Plectroninia_ and _Tretocalia_ (Fig. 68, D and E). Some diminutive forms also occur in the older series, the Balcombian, at Mornington, namely, _Bactronella parvula_. At Boggy Creek, near Sale, in Victoria, a Tetractinellid Sponge, _Ecionema newberyi_, is found in the Janjukian marls; spicules of this form have also been noted from the clays of the Altona Bay coal-shaft (Fig. 68 C). * * * * * The _ARCHAEOCYATHINAE_: an ancient class of organisms related both to the Sponges and the Corals. =Archaeocyathinae in Cambrian Strata.--=