Silurian Palaeechinoids.—
The Palaeechinoids are represented in the Silurian of Australia by occasional plates, as at Bowning, New South Wales, and near Kilmore, Victoria, whilst spines are not uncommon in certain Silurian limestones at Tyer’s River, Gippsland.
Carbopermian Palaeechinoids.—
In the Carbopermian of New South Wales, tests of Archaeocidaris have been recorded, and also a plate of the same genus in the Gympie Beds of Rockhampton, Queensland.
Regular Echinoids.—
The regular Echinoids date from Permian times. They have two vertical rows of plates for each ambulacrum and inter-ambulacrum. The mouth is on the underside, and the anus abactinal (on the upper side) and near the centre.
Fig. 80—CAINOZOIC SEA-URCHINS.
A—Cidaris (Leiocidaris) australiae, Duncan sp. Cainozoic (Janjukian). Cape Otway, Victoria
B—Psammechinus woodsi, Laube. Cainozoic (Janjukian). Murray River Cliffs, S. Australia
C—Fibularia gregata, Tate. Cainozoic (Janjukian). Aldinga, S.A.
D—Echinocyamus (Scutellina) patella, Tate sp. Cainozoic (Janjukian). Torquay, Victoria
E—Clypeaster gippslandicus, McCoy. Cainozoic (Janjukian). Bairnsdale, Victoria
F—Studeria elegans, Laube. sp. Cainozoic (Janjukian). Murray River Cliffs, S. Australia.