27 
III.— CONCLUSION. 
The fish fauna now described from the indurated shale of St. Peter’s 
is of special interest, because all the genera comprised in it are new to the 
Hawkesbury Formation, except Ilyriolepis, and perhaps Ealceoniscus. The 
aspect of this fauna is, indeed, distinctly older than that of the- Hawkesbury - 
Wianamatta fish-faunas previously discovered. Eleur acanthus, Sagenodus, 
Elonichthys, and Elatysomus are common in Europe in rocks even so old as 
the Lower Carboniferous ; but they range upwards partly to the Lower, partly 
to the Upper Permian. Ealceoniscus and Acentrophorus are essentially Upper 
Permian; while Elpisopholis is a genus which can scarcely he of earlier date 
than the Permian. The new St. Peter’s fauna may, therefore, best be termed 
Permo-Carboniferous. 
The discovery of the nearly complete skeleton of Eleuracanthus is 
fortunate, because it proves definitely that the Diplodont teeth of the 
Australian Hawkesbury Formation belong to the same type of shark as those 
of the European Carboniferous and Lower Permian strata. The known 
geographical range of the characteristically Permo-Carboniferous Ichthyotomi 
is therefore remarkably extended. The peculiarities of the dorsal spine, 
however, as well as the conformation of the anal fins, still remain unknown ; 
and better specimens of the head and branchial apparatus are much to be 
desired. 
The fragmentary skeleton of Sagenodus is of great interest when 
considered in connection with other recent discoveries of extinct Dipnoan 
fishes in Australia. There is now evidence of forerunners of the surviving 
Ceratodus in the Devonian of New South Wales, 1 'the Carboniferous of 
Victoria , 2 the Permo-Carboniferous and Triassic of New South Wales , 3 and 
the Jurassic of Victoria 4 It is thus clear that Dipnoi have always lived in 
the Australian region, and there is no reason why Ceratodus itself may not 
have evolved there. 
An undoubted Ealceoniscus has never hitherto been found in any 
formation beyond the Upper Permian, Kupferschiefer, and Marl Slate of 
1 Ganorhynehus Sussmilchi, R. Etheridge, jun., Rec. Austr. Mus., vi (1906), p. 129, PI. XXVIII. 
2 Ctenodus breviceps, A. S. Woodward, Mem. National Mus. Melbourne, No. 1 (1906), p. 15, Fig. 3. 
3 Qorfordia truncata, A. S. Woodward, Mem. Geol. Surv. N. S. Wales, No. 4 (1890), p. 5, PI. I, PI. II, 
Figs. 1, 2. 
4 Ceratodus avus, A. S. Woodward, Ann. and Mag. Nat. Hist. [7] xviii (1906), p. 2, PI. I Fig. 1. 
