100 
29th September, 1870. 
Read letter from Dr. J. M. Currier, Newport, Orleans County, 
Vermont, U.S., proposing to exchange ‘ The Archives of Science and 
Transactions of the Orleans County Society of Natural Sciences ’ for 
the ‘ Proceedings’ of this Club, and offering to furnish objects in 
exchange. 
Resolved, that the foregoing proposal be, with thanks, accepted. 
Mr. Vickers exhibited a ‘‘ mechanical finger’? which he had just 
designed and himself constructed for the purpose of assisting in the 
removal of individual diatoms under the microscope in order to mount 
them separately, by means of holding the ‘cover’ intended to 
receive the specimen in such a sloped position in focus of a low 
power of the microscope as would be suited to conveniently receive 
the example to be mounted, first on the edge of the cover so held, 
and then pushed up to its centre and final position by the hand. 
Mr. Vickers also exhibited stereoscopic transparencies taken with 
different parts of the same lens; these, when transposed, had a pseu- 
doscopic effect, proving that there is a real difference in pictures so 
produced. He therefore inferred that the images presented in the 
binocular microscope, being obtained in the same way, have a real 
difference, though produced by the one lens; hence the conclusions 
arrived at by appearance in the binocular microscope should be 
considered reliable. 
Mr. Crowe again showed Stephanosphera pluvialis from the 
original site, thus probably later in the year than it had hitherto 
been seen, 
Rev. HE. O’Meara exhibited a new and very handsome Pinnularia, 
of which he would soon furnish due description under the name of 
Pinnularia Vickersii. The same gathering (from stomachs of 
Ascidians, Roundstone Bay) afforded other fine forms; amongst the 
species presented was Donkinia compacta. 
Mr. Archer mentioned having met with for the first time the 
seemingly cosmopolitan, but certainly not abundant, little alga, best 
known, perhaps, under the name Botrydiwm argillaceum (Wallr.), 
but, doubtless, more properly called Hydrogastrum granulatum 
(Desv.), the latter name having the priority. He had often looked 
for this little denizen of the muddy bottoms of partially or nearly 
dried-up pools, but, strange to say, never before encountered it, 
though, no doubt, it will be found, under suitable circumstances, in 
various parts of the country. These specimens were taken from the 
bottom of the large pool to right of “ Rocky Valley,” near Bray, 
a pool so large and deep that he had often wished for a boat to 
explore its middle weedy parts; but this unprecedently dry summer 
had dried it up so nearly completely that you could traverse the 
whole site through and through, finding only here and there a few 
damp, not wet, spots. 
Mr. Archer brought for exhibition two new species of Staurastrum, 
one of Cosmarium (descriptions deferred), as well as the rare forms 
Olosterium prelongum (Bréb.), Desmidiwm aptogonum (Bréb.) 
