OF NEW SOUTH WALES. 23 



and differing, I imagine, from the Coral Reefs now forming, only 

 as Palaeozoic differs from recent Coral. A little further, and if 

 you are fortunate in cleaving the stone you will have a surface 

 presenting a strange confusion, on which it will be difficult to 

 find a spot not occupied by one of the fossil forms of the varied 

 Ufe of the old seas. Another will yield hardly anything but 

 Trilobites, jammed together heads and tails so thickly as to render 

 it difficult to procure a perfect specimen. 



I will now go back to our former starting point, and take the 

 Yass beds in the order of their deposition. Standing at the edge 

 of the igneous rock (a kind of syeuetic porphyry) where the 

 river enters the town on the east side, and turning westward, 

 you will look straight across the fossiliferous strata, which here, 

 with intervening Porphyry and altered rock, have a breadth of 

 from four to six miles. The view across the strata is interrupted 

 by the range west of the town. The mass of this range is 

 Porphyry. This Porphyry naturally divides the sedimentary 

 rocks into two parts — that portion to the east of the Porphyry 

 bending in one direction to the south-east over the Yass Plains, 

 and in the other marked by the course of part of the Bango and 

 Fairy-hole Creeks, I propose to call the Yass Beds. That 

 portion to the west of the Porphyry, and bending to the south- 

 east over the Yass Plains, and in the opposite direction, west of 

 north, along a course marked by part of the Derringullen and 

 Limestone creeks, to about a mile above the junction of these two 

 creeks, I propose to call the Hume Beds — these beds being so 

 largely developed on the property that belonged to the late 

 Hamilton Hume, Esq., our great explorer. 



Starting then on the edge of the Yass Beds, following the 

 river, we have first a few feet of altered strata, a thin layer 

 of limestone, then two feet of fossil bearing strata. Of species 

 obtained hence there are four Brachiopods, including a small 

 Lingula and an Atrypa ; three Gasteropods, including one very 

 like Bellerophon acutus ; an impression of a rather large 

 Orthoceras, and a number of very small things not made out. 



Then follows some black, slaty-looking shale, cleaving readily 

 in the direction of the bed. These beds gradually become more 



