+4 Reports & Proceedings—Mineralogical Society. 
2. December 1, 1915.—Dr. A. Smith Woodward, F.R.S., President, 
in the Chair. 
The President exhibited lantern-slides lent by Professor Elliot 
Smith to illustrate the fossil human skull found at Talgai, Darling 
Downs, Queensland, in 1914. The specimen was brought to the notice 
of the British Association in Sydney by Professor T. W. Edgeworth 
David, and would shortly be described by him and Professor Arthur 
Smith. It was obtained from a river-deposit in which remains of 
Diprotodon and other extinct marsupials had already been discovered, 
and there could be no doubt that it belonged to the Pleistocene fauna. 
It therefore explained the occurrence of the dingo with the extinct 
marsupials. The skull is typically human and of the primitive 
Australian type, but differs from all such skulls hitherto found in 
possessing relatively large canine teeth, which interlock like those of 
an ape. The upper canine shows a large facet worn to its base by the 
lower premolar. The discovery of the Talgai skull is, therefore, an 
interesting sequel to that of Mr. Charles Dawson’s Piltdown skull, in 
which the canine teeth are even more ape-like. 
Dr. J. W. Evans discussed the different methods of obtaining the 
directions-image (‘‘interference figures’’) of a small mineral in © 
a rock-slice, unaffected by the light from neighbouring minerals. 
He preferred the use of a diaphragm in the focus of the eye-piece, in 
conjunction with a Becke lens. 
He also described the inferences that might be drawn from the ~ 
form, position, and movement on the rotation of the stage of the 
isogyres (dark bars or bushes) in the directions-images, both of 
chance sections and those cut parallel to planes of optical symmetry 
or at right angles to optical axes. He showed how the character or 
sien of the crystal and its approximate optic axial angle might be 
determined. 
IIT.—Mineratoeicat Sociery. 
Anniversary Meeting, Movember 9, 1915. W. Barlow, F.R.S., 
President, in the Chair. 
W. Barlow: Crystallographic relations of allied substances traced 
by means of the law of valency volume. ‘The ordinary parameters 
of a crystal do not necessarily express the actual ratio between the 
minimum translations of the crystal structure, and it is justifiable to 
multiply one or sometimes two of them by a small integer in order to 
obtain the equivalence parameters. A number of cases were taken 
which showed that in crystals which either contain the same radicle 
or closely related radicles the similar parts are arranged in identical 
strata intercalated between the remaining constituents of the crystal. 
A. F. Hallimond: On Torbernite. From measurements made on 
several specimens the axial ratio a: ¢ = 1: 2'947 was determined, 
and the forms 001, 101, 108, 111, 112, besides vicinal faces, were 
observed. The mineral becomes unstable at vapour-pressures about 
one-third that of water, and passes into Rinne’s meta-torbernite I. 
At higher temperatures the transition-curve rises sharply, and meets 
the vapour-pressure curve of water at 75° C., above which torbernite 
has no stable existence in air. T. V. Barker: On the solution 
