35 | 
iferous System, and that only certain minor ridges, like that 
at Spring Hill, represent diabasic greenstones of a later date. 
There is little difficulty in distinguishing these Upper 
Palaeozoic and Mesozoic greenstones from the sheets of 
basalt, which, with their associated tufts, so frequently over- 
spread the Tertiary lignites and leaf beds, and which 
probably mark the close of the Tertiary Paleogene period in 
Tasmania. 
The rocks of the Carboniferous System invariably present a 
very uniform character throughout the southern part of Tas- 
mania. In the Basin of the Mersey there is greater variation, 
caused by a temporary local elevation and subsequent de- 
pression of the floor of an old arm of the Upper Paleozoic 
sea, between which elevation and depression sedimentary, 
deposits of carbonaceous matter of considerable thickness 
were formed, derived from a luxuriant land vegetation con- 
sisting of Club mosses, from which the spores of Tasmanites 
punctatus were no doubt derived. Ferns and Equisetaces 
were also abundant, as indicated by the remains of Glossop- 
teris Gangamopteris and Schizoneura. 
The bituminous Tasmanite shales were deposited in an 
arm of the sea, not in fresh water, as shown by the abundance 
of the remains of marine mollusca found in the Tasmanite 
notably Aviculopecten squamuliferus, A. Fittoni, Pleurotomaria, 
Woodsti, Pachydomous, Pterinea lata, s.p. and several other 
forms common to the marine beds above and below the 
Mersey Coal Measures. 
Until very recently, I was in doubt whether the marine 
mudstones and limestones in the neighbourhood of Hobart, 
and in the South generally, represented the lower marine 
beds only, or whether they represented in one continuous 
series the upper and lower marine beds as developed in the 
Mersey Basin. The possible existence of the Lower Coal 
Measures underlying the marine mudstones made this a very 
important question, and it was this consideration which 
induced the Government to make the test at the Cascades 
already described, but which demonstrated the fact that no 
coal existed beneath the mudstones at this point. Before this 
practical test, little value could be attached to conclusions 
formed upon the partial evidence of marine fossil organisms 
alone, because a considerable per-centage of the species of the 
the marine organisms common to the mudstone series over- 
lying the Mersey Coal Measures was also common to the 
underlying or lower marine beds, and also to the Tasmanite 
eroup. Among the fossils common to these deposits are the 
well-known forms:—Spirifera Tasmaniensis, S. Darwinit 
Terebratula sacculus, Productus brachythyerus, Pterinea lata, 
Sanguinolites Htheridget, Pecten Fittoni, P. squamuliferus, P- 
