232 JOURNAL OF SCIENCE, 
In the discussion which followed the reading of Mr. Stephens’ 
paper, Mr. R. M. Johnston stated that little value could be placed 
on conclusions formed from the partial evidence of marine or- 
ganisms only, as regards the position of the Southern and Eastern 
coal deposits of Tasmania, because he had found a considerable 
percentage of the species of the marine organisms common to the 
mudstone series immediately overlying the Mersey coal measures 
also common to the mudstone series which is now being tested by 
the boring drill at the Cascade Brewery, and also common to the 
Tasmanite beds on the Mersey. Among the fossils common to 
these deposits are the well-known forms :—Spirifera Tasmaniensis, 
Spivifera Darwinit, Productus brachythyerus, Pterinea lata, Sanquinolites 
Etheridgei, Pecten Fittom, Pecten squamuliferus, Pecten Illawarra, Peeten 
nov. sp., Pleuvotomaria Morrisiana, Protoretepova ampla, Stenopova Tas- 
maniensis, and several others, and the list no doubt could be greatly 
increased. If, therefore, it be allowed that the Mersey and 
Southern and Eastern coal deposits represent different horizons, 
the evidence from marine organisms, taken by itself with our 
present knowledge, is absolutely valueless, at any rate neutral. 
It is from an examination of the plant remains, associated with the 
respective coal measures, that we have any grounds for separating 
them into difterent groups, as representing different periods. Thus 
the prevailing plant remains of the coal measures of the Mersey, 
which are the equivalents of the Stoney Creek, Anvil Creek, and 
other coal seams in New South Wales, are Glossopteris Browmana ; 
eqisetaceous stalks, broadly and flatly ribbed, allied to the Indian 
genus Schizoneuva ; a curious orbicular form allied to Actinopteris ; 
and numerous impressions ofa form closely allied to Noeggerathiopsis 
media. On the other hand, the Midland, Southern and Eastern 
coal measures of Tasmania have generally as prevailing forms Pe- 
copteris Australis, P. odontopteroides, Phyllotheca Hookeri, Phyllotheca 
yamosa, Sphenopteris alata, Zeugophyllites elongatus, and Glossopteris 
linearis, and, therefore, the beds may, without doubt, as already 
shown by Feistmantel, Rev. W. B. Clarke, R. Etheridge, junr., and 
others, be regarded as the equivalents of the upper coal measures of 
New South Wales. Regarded from an evolutionist’s point of view, 
Mr. Johnston stated that, with the late Rev. W. B. Clarke, he found 
it very difficult to recognise any break, stratigraphic or organic, 
between the upper and lower mudstone series of Australia, so far 
as the marine organisms of undoubted palzeozoic facies gave any 
evidence. If these subdivisions were to be classed as upper palzo- 
zoic, and the upper coal measures, according to various authori- 
ties, aS permian, oolitic, dias, or mesozoic, the separation must be 
doubtful and purely one of local convenience. Mr. Johnston ob- 
served that while, on the whole, he fully agreed with Mr. Stephens’ 
conclusions, he was not prepared to concur with him in regarding the 
sandy and calcareous fossiliferous rocks occurring in the neighbour- 
hood of Hobart, and in other localities in the South and East, wholly 
as the equivalents of the lower marine beds of New South Wales, for 
it was not only conceivable but, unfortunately, probable that the 
Southern marine beds ot Tasmania were formed in situations more 
removed from the oscillation of the land which produced the con- 
ditions favourable to the deposits of the lower coal measures in 
such places as the Don, Mersey, Stoney Creek, and Anvil Creek 
basins ; that while these carbonaceous deposits intercalating and 
