46 
length down. It was very interesting to watch the 
creatures push this door open as they emerged from their 
tubes. 
These last two species I had not found before. 
Rough diagrams of each of the creatures mentioned were 
exhibited by Mr. Boyd, and slides of Leptodora, Sida, 
Dioptomus, and Polyphemus. 
Mr. R. Ellis Cunliffe exhibited various interesting 
microscopical slides. 
Mr. Rogers exhibited a living specimen of an Ampullaria 
from Assumoroi, River Niger, West Africa. It had remained 
quite dormant for a considerable period, but was now in a 
thriving condition. 
The following paper was read at the meeting held on 
October 19th, but only part of it printed in the last number 
of Procedings : — 
“ On some early Anticipations of Heliographic Signalling,” 
by William E. A. Axon, M.R.S.L. 
The use of the heliograph in war is likely to gain ground. 
Nature (April 29, 1880, vol. xxi., p. 617) gives an instance 
in which a message was flashed by this means as speedily 
as by the electric telegraph. The following description is 
given of the modus operandi : “The line of communication 
cannot be cut, for the simple reason that the signalling 
takes place over the heads of the enemy, and the stations 
required are but few and far between. A 10-inch mirror— 
and this is the diameter of the ordinary field heliograph — is 
capable of reflecting the sun’s rays in the form of a bright 
spot, or hare, to a distance of fifty miles, the signal at this 
