Devonian Scaphopods.—
This group of mollusca makes its first appearance in Australasian sediments in the Middle Devonian (Murrumbidgee beds) of New South Wales, represented by Dentalium tenuissimum.
Jurassic Scaphopods.—
In the Jurassic strata of the Mataura Series of New Zealand, Dentalium huttoni ([Fig. 97 A]) occurs at the Kowhai River and Wilberforce.
Cretaceous Scaphopods.—
Dentalium wollumbillensis occurs in the drab and dark-coloured limestones of the Lower Cretaceous of the Lake Eyre Basin in S. Australia, and the same species is also found in the Lower Cretaceous (Rolling Downs Formation) of Wollumbilla, Queensland.
Cainozoic Scaphopods.—
The Cainozoic beds both of New Zealand and southern Australia yield many species of Dentalium, the commonest and most widely distributed being the longitudinally ribbed D. mantelli ([Fig. 97 B]), which ranges from the Balcombian to the Werrikooian stages in Australia, and is also typical of the Oamaru Series in New Zealand, where it is accompanied by the ponderous species, D. giganteum, which attained a length of over six inches. Another form common in our Cainozoics is the smooth-shelled D. subfissura; this also has a wide range, namely Balcombian to Kalimnan.
Palaeozoic Chitons.—
The POLYPLACOPHORA or Chitons (“Mail-shells”), first appeared in the Ordovician. In Australia Chelodes calceoloides ([Fig. 97 C]) is found in the Silurian of Derrengullen Creek, Yass, New South Wales; and another species of the genus is found in beds of the same age at Lilydale, Victoria. Between that period and the Cainozoic or Tertiary there is a gap in their history in Australia.