Silurian Stromatoporoids.—
In the Silurian limestones of Victoria (Lilydale, Waratah Bay, Walhalla and Loyola), and New South Wales (near Yass), Stromatoporoids belonging to the genera Clathrodictyon (probably C. regulare), Stromatopora and Idiostroma occur. Stromatoporella has been recorded from the Silurian rocks of the Jenolan Caves, New South Wales.
Devonian Stromatoporids.—
The Middle Devonian strata of Bindi, Victoria, yield large, massive examples of Actinostroma. This genus is distinguished from the closely allied Clathrodictyon by its vertical pillars passing through several laminae in succession. Rocks of the same age in Queensland contain Stromatopora, whilst in Western Australia the Rough Range Limestone has been shown to contain Actinostroma clathratum ([Fig. 72 A, B]) and Stromatoporella eifeliensis.
Cladophora.
Palaeozoic Cladophora.—
Some branching and dendroid forms of Hydrozoa probably related to the modern Calyptoblastea (“covered buds”), such as Sertularia and Campanularia, are included in the Cladophora (“Branch bearers”). They existed from Cambrian to Devonian times, and consist of slender, forking branches sometimes connected by transverse processes or dissepiments, the branches bearing on one or both sides little cups or hydrothecae which evidently contained the polyps, and others of modified form, perhaps for the purpose of reproduction. The outer layer, called the periderm was of chitinous material. They were probably attached to the sea-floor like the Sertularians (Sea-firs).
Dictyonema and Allies.—
Remains of the above group are represented in the Australian rocks by several species of Dictyonema ([Fig. 72 E, F]) occurring in the Lower Ordovician of Lancefield, and in similar or older shales near Mansfield. Some of these species are of large size, D. grande measuring nearly a foot in width. The genera Callograptus, Ptilograptus ([Fig. 72 C, D]) and Dendrograptus are also sparsely represented in the Upper Ordovician of Victoria, the two former from San Remo, the latter from Bulla.