110 PROCEEDINGS OF SECTION C. 



In the quarry itself I only found fossil remains represented by 

 crinoid stems and ossicles, and some Favosites. Some of the crinoid 

 stems are about three-quarters of an inch in diameter, the largest 

 I have found in the Yass district. In one sample of limestone the 

 matrix was of a very light grey, and the crinoid remains were pink. 



Nearer Bango Homestead Halysites was found, a genus searched 

 for in the Yass beds for some years. The specimens were fairly 

 plentiful in the limestone, and from a micro-section of one con- 

 sidered to be Halysites pycnohlastoides, Eth. fil. 



Mr. W. S. Dun, of the Geological Survey of N.S.W., has since 

 shown me a specimen of Halysites, recently discovered by Mr. E. F. 

 Pittman, Government Geologist, at Canberra, which strengthens 

 my behef that the Canberra beds will be found to be a continuation 

 of the Bango beds, and in all probability the beds there have not 

 been subjected to so much destructive metamorphism as at Bango. 



Other fossils since found at Bango are : — Tryplasma (2 new 

 species) ; Heliolites, Pachypora, Chcetetes, {?), Cyathophylluni, Stro- 

 matopora, (?) Cyclonema, and fragments of bivalves. On the right 

 bank of Bango Creek, in altered mudstones — Arenicolites. 



The thickness of the bed of limestone was not determined, as 

 the outcrops consist mainly of weathered boulders projecting 

 through the soil, but from its appearance in the quarry (PI. lY. 

 Fig. 3) the deposit should be very solid at a depth. From the 

 quarry back to the 183 mile peg, the country consists of such a 

 confusion of porphyry, altered sediments, small patches of lime- 

 stone, and fossiliferous porphyry, that with the short time at my 

 disposal I was unable to obtain anything like a clear insight as to 

 the sequence of the various beds. 



No. 2 Porphyry. — To the west of this limestone belt the 

 country is just as complicated, as a cursory trip across it, as far as 

 Derrengullen Creek, seems to produce nothing but quartz porphyry. 

 Closer scrutiny, however, brings to light in what looks like massive 

 porphyry unmistakable silurian fossils. At the junction of the 

 Rye Park and Blakney Creek roads, on W.R. No. 118, Parish of 

 Bango, the blue black porphyry contains limestone and shale 

 fragments, together with fossils, such as Favosites, Cyathophylluni, 

 crinoid stems, and remains of brachiopods. Portions 160 and 153 

 in the same parish also yield the fossiliferous porphyry, and altered 

 mudstones. 



Two samples of rock from portion 138 were submitted to Dr. 

 W. G. Woolnough, University of Sydney, who has kindly under- 

 taken to examine a series of the Yass porphyries. He has not yet 

 had time to make complete determinations, so that his reports are 

 only preliminary ones. He identifies some as quartz porphyry, 

 others undoubtedly quartz porphyry tuff. 



At Oak Range, about a mile to the west, on portions 56 and 99, 

 Parish Derrengullen, the porphyry is in places very coarsely spheru- 

 litic, and in places splits into slabs, from a few inches to a foot or 

 more thick, which only require a httle trimming to make them 

 suitable for door steps, and other building purposes. An outcrop 



