Cambrian Crinoids.—
The group of the Crinoidea first appears in the Upper Cambrian, and persists to the present time. In North America the genus Dendrocrinus occurs in the Cambrian and Ordovician; and some stem-joints from the Upper Cambrian limestone of the Mount Wellington district, Victoria, may be provisionally referred to this genus.
A—(?) Pisocrinus yassensis, Eth. fil. Side of calyx. Silurian. Yass, New South Wales.
B—(?) Pisocrinus yassensis, Eth. fil. Dorsal Surface. Silurian. N. S. W.
C—Botryocrinus longibrachiatus, Chapm. Silurian. Flemington, Vict.
D—Helicocrinus plumosus, Chapm. Stem, distal end. Brunswick, Victoria.
E—Phialocrinus konincki, Eth. fil. Carbopermian (Up. Mar. Ser.) Nowra, New South Wales.
F—Isocrinus australis, Moore sp. L. Cretaceous. Wollumbilla, Q’ld.
Ordovician Crinoids.—
No undoubted Crinoid remains have been found in the Australian Ordovician; although many genera are found elsewhere in that system, chiefly in N. America, as Reteocrinus, Hybocrinus, Heterocrinus and Dendrocrinus, and in Europe and North America, as Rhodocrinus and Taxocrinus.
Silurian Crinoids.—
The Silurian Crinoidea of Australia are largely represented by the remains of the columns or stalks, which are often found in such abundance as to constitute large masses of sub-crystalline limestone, as that of Toongabbie, Victoria. The columns of the Crinoids do not usually possess sufficient characters to enable the forms to be identified. There are, however, more perfect and identifiable remains of several very interesting generic types in the Silurian faunas as follows:—