48 .- - LIVERPOOL BIOLOGICAL SOCIETY: 
Brittany coast, and made some very interesting observa- 
tions and experiments at St. Malo with the acorn-shell, 
Balanus balanoides, which is so commonly found at the 
extreme upper edge of the littoral zone on rocky coasts. 
Vaillant found that this marine animal, although it can 
only expand and obtain food when covered with water, is 
able to live so far above ordinary high-water mark as to 
remain dry for days at a time, amounting on an average 
to eighteen or nineteen-twentieths of its life; and he 
determined by experiment that it can live out of water for 
at least forty-four days at a time. 
These observations are particularly interesting to me, 
as, before hearing in Paris last summer of Vaillant’s work, 
I commenced some almost exactly similar observations at 
Hilbre Island, in 1885* and at Puffin Island in 1887, 
from which I made out that the Polyzoon Flustrella 
hispida, which is found within a yard of ordinary high- 
water mark, must be exposed to the air during about 
five-sixths of its existence, and can only feed during the 
remaining one-sixth at and about the time of high tide. 
Probably respiration can be carried on to a certain extent. 
both in the case of this animal and of Vaillant’s Balani 
by a little air being let in periodically to oxygenate the 
small quantity of sea-water shut in with the body of the 
animal. 
EXPERIMENTS ON HARPACTICIDA. 
One of the first things one notices on examining the 
zones of life upon the shore at Puffin Island is that there 
are certain marine animals above high-water mark. There 
are some pools in the rocks which are only reached at high 
spring tides, or perhaps only by the spray from the waves” 
during storms. These are overgrown with a common 
* See Liverpool Datly Post, 15th June, 1885. 
