A—Palaeaster smythi. McCoy sp. Silurian. Flemington, Victoria.
B—Urasterella selwyni, McCoy. Silurian. Kilmore, Victoria.
C—Palaeaster giganteus, Eth. fil. Carbopermian. Near Farley, New South Wales.
D—Pentagonaster sp. Tertiary (Janjukian). Bore in Mallee, Victoria.
Silurian Starfishes.—
The oldest Australian fossil Starfishes are found in the Silurian. In Victoria they occur in some abundance in the lower, Melbournian, series, but appear to be absent or at all events very scarce in the upper, or Yeringian series. The commonest genus is Palaeaster, of which there are two species, P. smythi ([Fig. 77 A]) and P. meridionalis, found alike in the sandy and argillaceous strata near Melbourne. Urasterella is another genus found in the Silurian rocks near Melbourne, in which the marginal series of plates seen in Palaeaster are wanting, giving to the starfish a slender, long-armed aspect ([Fig. 77 B]).
Carbopermian Starfishes.—
In the Lower Marine Series of the Carbopermian of New South Wales a very large species of Palaeaster occurs (P. giganteus), measuring 7 inches from point to point across the disc ([Fig. 77 C]). Two other species of the same genus occur in this series (P. stutchburii and P. clarkei) the latter also ranging into the Upper Marine Series.
Cainozoic Starfishes.—
No remains of true Starfishes have been recorded from Australia between the Carbopermian and the Tertiary systems. In the Janjukian Series of Victoria the marginal plates of a species of Pentagonaster are typical fossils. They have been recorded from Waurn Ponds, Spring Creek near Torquay, and Batesford ([Fig. 77 D]). In the Mallee Bores, both marginal and abactinal plates of this genus are found in polyzoal limestone (Miocene). Pentagonaster also occurs in the Lower Muddy Creek beds (Oligocene), and the Upper beds of the same locality (Lower Pliocene). A species of Astropecten has been described from the Waikari River, New Zealand (Oamaru Series).