328 C. F. LASERON. 
separated by lenticular beds of a fine grained sandstone. 
At this spot they exhibit some remarkable examples of 
weathering. In several rock shelters numerous sheets of 
sandstone a foot across were flaking off, across the strati- 
fication, and were frequently not more than one-eight of an 
inchin thickness. In other places regular jointed beds had 
had their cracks filled with iron oxide. Subsequent decom- 
position of the sandstone had left a peculiar boxlike arrange- 
ment of limonite, sometimes standing out as a framework 
two or three feet from the wall. The well known honey- 
comb weathering familiar in the Hawkesbury sandstone 
was very common. 
It is worthy of note that these beds, though much finer 
than the conglomerates beneath, are still very coarse. It 
is evident that only the strongest shells would stand a 
chance of preservation. Inthe conglomerates on the other 
hand it is doubtful if any organism would remain intact. 
Thus we find two tough shells in the forms of Hdmondia 
nobilissima and Mceonia elongata in the EKdmondia sand- 
stones, and with the exception of one or two Spirifers and 
a little bivalve found in abundance in a ferruginous sand- 
stone overlying the Edmondia horizon, these were the sole 
fossils. This fossil bivalve is important, as it occurs right 
throughout the Wandrawandian Series being found about 
the same horizon on the western and north-eastern sides 
of Sugarloaf, at Grassy Gully and in the Burrier mudstones. 
As exemplyfying the turbulent conditions prevailing when 
the Edmondia beds were deposited, I might mention that we 
were for some time puzzled as to the nature of certain 
fragments of shell with a fibrous structure; these were 
very common, but never more than one inch across. At 
Grassy Gully, however, we found large specimens of 
Aphanaia gigantea with the shell complete, which corres- 
ponded with the fragments found; evidently this mollusc 
