Reports & Proceedings—Geological Society, Glasgow. 335 
Fine specimens of split and eroded cherts from Oligocene gravels 
were shown. 
V.—GerotoeicaL Socrery, Grascow. 
At a meeting of the Geological Society of Glasgow on May 11, 1916, 
Mr. Macnair exhibited a series of specimens got from the ancient bed 
of the Clyde in the course of digging the foundations of the new 
Dalmarnock Power Station. The specimens consisted of hazel-nuts, 
twigs and timber, and the epidermis of pearl mussels. The pearl 
_ mussels had lost all trace of their calcareous shells through the action 
of percolating water, and only the chitinous epidermis remained, 
resembling dead leaves in brittleness and form. He pointed out that 
the occurrence of such relics had been recorded about half a century 
ago 1n proximity to the present course of the Clyde, and there could 
be no doubt that they came from the same bed which also contained 
human relics in the shape of dug-out canoes. 
Professor J. W. Gregory read a paper on ‘‘ The Auld Wives’ Lifts: 
a Pseudo-Megalithic Tor’. He described the position of the well- 
known stones and referred to the traditional explanation of their 
origin, which ascribes them to a trial of strength between three 
witches of the district. For long the stones have been regarded as an 
example of a cromlech erected by the race which has dotted the 
country with megalithic structures. Careful examination, however, 
has shown that the group is purely the result of natural processes of 
denudation isolating a portion of the gritty sandstone of the district 
which had been dismembered and the fragments thrown into their 
present attitude by slipping along joints and bedding planes. It was 
shown that this could be proved by the fact of the existence of the 
lines of fracture of prominences corresponding with hollows on the 
opposite block. ‘ 
Mr. Ludovic McL. Mann pointed out that although the erection of 
the blocks could not be ascribed to man and the structure differed in 
' some respects from the typical cromlech, there could be no doubt that 
it had been adopted by the early inhabitants of the district. He 
believed that the upper surface of the capstone had been levelled by 
the prehistoric process of ‘ knapping’ and had then been sculptured, 
the traces being quite evident to the trained eye. Other evidence 
also showed that the district had been one of special interest to the 
early inhabitants and was now of importance to the archeologist. 
VI.—Mrnzratoetcan Sociery. 
June 20.—Dr. A. E. H. Tutton, F.R.S., Past-President, in the Chair. 
Dr. J. W. Evans: The Relations between different Laws of 
Twinning giving the same Twin-crystal. If the untwinned crystal 
has no symmetry, different twin-laws give different results. In the 
presence of a centre of symmetry an axis of rotation-twinning is an 
axis of reflection-twinning. An axis of rotation-twinning lying in 
a plane of symmetry has at right angles to it in the same plane an 
axis of reflection-twinning. If the normal to a plane of symmetry 
be an axis of rotation-twinning, or if a line of symmetry (axis of even 
symmetry) be an axis of reflection-twinning, the same result may be 
