4 
The occurrence of Trilobites, fyc. 
rock, which in many cases divides the casts with the limestone. 
That particular fossil I have provisionally named P. Macarthuri , 
At some future time, if opportunity allows, I intend to search that 
locality for Trilobites. For the present I will only remark, that 
1 have laid before the Geological Society* some remarks on thf} 
occurrence of dykes of marble and quartz rock in granite in tb§ 
bed and banks of the Wollondilly, near Arthursleigh; and sineft 
my paper was read I have discovered in the marble a few miles 
distant, which I know to have similar relations with quartz rock, 
traces of corals. Hitherto that marble, which is in some places 4 
pure crystalline white Carrara marble, has been considered, as 1 
stated it to be, without fossils; but it is now found to be fossilife- 
rous. As it is associated with various granitic traps and greeA 
stone, its crystalline structure and general freedom from fossils 
may be due to igneous agency. There can be no doubt that 
numerous organic remains distinguish the rocks of this class all 
over New South Wales; and amongst others I have a Fucoid, 
which I found in the siliceous rocks of Colocolo, associated with 
orthides and turbinolopsis, and which much resembles F. antiquus 
of Brougniart’s Vegetaux Fossiles (4, fig. 1). 
As my object in this brief account is chiefly to make known the 
occurrence of Trilobites in the ancient deposits of Australia, and 
to claim priority for the first discoverers, I purposely abstain from 
the mention of other facts, bearing on the presumption that the 
inclined beds underlying the coal deposits of New South Wales 
belong to true Silurian types, though it is neither wise nor safe, 
perhaps, at present to attempt to classify them by European deno¬ 
minations. Among other determined Silurian fossils, Favosiles 
Gothlandica is a well-known species in the rocks near Yass and 
elsewhere. My own collection of New South Wales fossils, which 
amounts to considerably more than one thousand species, would 
probably furnish many other points of comparison! 
• 
Paramatta, 29 th May, 1846. 
* Journal of Geological Society, vol. i. p. 342. 
