PROCEEDINGS OF SOCIETIES. 73 
small shreds of meat, rasped boiled liver, and the like. For 
the marine creatures, raw meat dried in the sun and moist- 
ened when used, answers very well. Oyster, mussel, cockle, 
raw fish, shrimps, and the like matters may be employed ; 
these should be cut or pulled into very small pieces, and 
never more given than they can at once appropriate ; and if 
rejected by one, it should be transferred to another, or re- 
moved from the tank. In the case of Actinia, they require, 
from their fixed position, that the food should be guided to 
their tentacles ; and if the animal food, of whatever kind, is 
soaked in a little water, and the water thus impregnated with 
animal fluids be dropped in moderate quantity into the tank, 
it will afford food for the small Entomostraca and smaller 
creatures with which the water abounds, and which constitute 
the food for many of them. 
A few observations were also made on the construction of 
a microscope for the purpose of employment in connection 
with the aquarium, and the method in which such an instru- 
ment could be used.—R. W. 
Dustin University ZooLocicaL AND BoTanicaL ASsocIATION, 
January 16th, 1857. 
R. Ball, LL.D., President, in the chair. 
Catalogue of Desmidiacee. By Wm. Arcuer, Esq. 
Tue following list of the Desmidiaceze which I have found 
about the “ Feather-bed”’ and “ Seechon” mountains, near 
Dublin, is not, of course assumed to be a complete list. It 
is, however, a perfect one (with, perhaps, the exception of the 
genus Pediastrum) of the species I have met with in my 
limited experience; and I have no doubt but subsequent 
search will very much extend it. I have ventured to append 
to each species an opinion as to its frequency or rarity, which, 
I need hardly state, is to be interpreted as the result of my 
own experience only in a limited district. Some of those I 
have marked as rare may ultimately prove frequent. I am 
inclined to corroborate an observation made in Mr. Ralfs’ 
beautiful ‘ Monograph,’ as to the non-occurrence of the same 
species in the same pools from year to year. For instance, 
in the year 1855, a certain pool produced Didymoprium Bor- 
reri in great abundance. During 1856 I could not find a 
single specimen of that species; but its place was taken by 
a considerably less abundant development of AHyalotheca 
mucosa. 
