SILL STRUCTURE AND FOSSILS IN ERUPTIVE ROCKS. 285 
It comes under the heading pyrope ; probably is pyrope. 
The specific gravity, colour, analysis, and the mode of occurrence 
all agree with pyrope. The specimen is pyrope. 
This method may be faulty, but it is given in detail, as a charge 
of “recklessly ignoring” is one not often heard in scientific circles. 
It will be for others to judge if the above process smacks of reck- 
lessness. I would conclude by saying that I value highly the 
privilege and right of every member of our Society to criticise 
papers placed before the members. But criticism of the kind to 
which I have now replied, surely goes beyond that limit of 
dispassionate and courteous treatment which we have alla right 
to expect. 
SILL STRUCTURE anv FOSSILS 1m ERUPTIVE ROCKS 
In NEW SOUTH WALES. . 
By Professor T. W. EpaewortH DavID, B.A., F.G.S. 
[Read before the Royal Society of N. 8. Wales, November 4, 1896.] 
Introductory.—Sill structure has long been known to play an 
important part in the architecture of the earth’s crust. The 
development, however, of sill structure in New South Wales is 
80 wonderfully extensive and complex as to justify a special 
description, inasmuch as it promises to revolutionize. prevalent 
ideas, at all events in Australia, as to the nature of the junction 
line between eruptive rocks and sedimentary rocks, and satisfac- 
torily explains the apparent anomaly of the occurrence of fossils 
in eruptive rocks, IT propose therefore to offer a short preliminary . 
hote on this subject. 
Bibliography.—Professor Judd has described sill structure in 
the Mesozoic rocks of Scotland.! Reyer has described in detail 
ey the Ancient Volcanoes of the Hebrides and the Relations of 
‘On 
their Products to the Mesozoic Strata.—Quart. Journ. Geol. Soc. 1874, 
pels Xy P. onder pl. xxii. - xxiii, and Abstract in 1878, Vol. xxxtv., 
