330 
PROCEEDINGS OF SOCIETIES. 
Slides Nos. 13 and 14 are sections cut from rock taken from 
different points on Mount Davidson and sent to me as specimens of 
the Mount Davidson syenite. On examination it will be seen that 
the feldspar is not orthoclase, so that it is a diorite, instead of a 
syenite. I will try and procure some more specimens and submit 
them to the Society at some future meeting. 
The regular meeting of the San Francisco Microscopical Society 
was held on Thursday evening last, with Vice-President H. C. Hyde 
in the chair. 
Dr. J. H. Wythe donated two slides mounted with A. Ehrenhergii 
and L nervosa as opaque objects, which were obtained from Monterey 
Bay. 
Mr. J. P. Moore presented the Society with the fungoid growth 
which he described at the last meeting of the Society, and named 
Agaricus tridens. He made a statement to the effect that when the 
mycelium first begins to make its appearance on the timbers in the 
drifts of the mines, it presents a pure white appearance, and seems 
to burst out of the wood. It is called by the miners, the Lily of the 
Mines. 
Mr. H. G. Hanks presented some specimens of gold on crystals of 
pyrites, which seemed to have been squeezed from the pyrites. He 
also presented a sample of pure ground coffee and another of the 
ground articles of commerce, which a microscopic examination by him 
showed to be nearly 50 per cent, chicory. 
Mr. Henry Edwards presented a quantity of diatomaceous earth, 
from near Los Angeles, containing many interesting fossil forms of 
the beautiful silicious frustules ; and from the bottom of Lake Tahoe, 
600 feet below the surface, came similar forms to bear them company, 
obtained by Dr. Blake, on a recent visit to that locality. Dr. Blake 
also exhibited two varieties of entomostraca, found in myriads in the 
surface waters -of the same lake, but which were passed over for the 
present with a cursory examination. 
Mr. J. P. Moore exhibited a super-stage, which he had caused to 
be made from a model described in the ' Quekett Journal of Micro- 
scopy,' the advantages of which he stated at some length, and which 
he had verified recently. 
Dr. J. H. Wythe brought to the rooms his Crouch binocular 
instrument, for the purpose of exhibiting some further improvements 
made in his oblique condenser and amplifier. His tests with a low 
power over P. angulatum and >S^. gemma for magnification and defi- 
nition at the same time, were conclusive as to the merits of both 
accessories. Dr. Wythe stated to the members present that he had 
taken the liberty of dedicating his forthcoming work on microscopy to 
the San Francisco Microscopical Society, and that the volume was in 
the press, and would soon be out. 
