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The identifiable fishes of the grey mudstone are distinctly newer in 
type than those of the black indurated shale, and would he termed Triassic or 
Rhsetic, if found in the northern hemisphere. The only doubtful species is 
Palceoniscus anlipodeus, which does not appear to have been seen until now 
since Egerton originally described it from Cockatoo Island. Semionutus is 
essentially Triassic or Rhsetic wherever it be found, — whether in Europe, 
North America, or South Africa, — and species of this genus occur with 
Cleithrolepii in the grey mudstone at Gosford. Pholidophorus is typically 
Jurassic, but also ranges downwards to the Rhsetic and Middle Trias in 
Europe. The fishes from the St. Peter’s mudstone are, indeed, closely similar 
to those from Gosford, and it is difficult to explain their occurrence on the 
same geological horizon as those from the black indurated shale already 
described. 
