154 YRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
such a pond, the only one that now seems possible to 
biologists and engineers alike, is to build the concrete tank 
above the ground on the garden site close to the engine- 
house. Here there is space for a pond 60 feet by 20 feet, 
and 10 feet deep, which would have a capacity of about 
75,000 gallons. Our present pumps are capable of supply- 
ing about 2,500 gallons per hour, and the tides allow of 
pumping for about 4 hours out of 12, two and a half hours 
before and one and a half hours after high water. When 
the pond is full it would be possible to change at least 
one-seventh of the whole contents each tide, and in the 
intervals between the periods of pumping this seventh 
part, over 10,000 gallons, would be used for working the 
apparatus in the tank room. It is most desirable that 
permission to proceed with the erection of the required 
pond be obtained from the Board of Trade with as little 
delay as possible. Such a pond could be made available 
for various useful purposes, such as fish spawning, lobster 
hatching and rearing, and oyster spatting and cultivation. 
In the early spring over 600 mature fish could be accom- 
modated, which should provide an abundant suvply of eggs 
for the hatching boxes.* 
At the close of each fish-spawning season 1t would pro- 
bably be necessary to set the spawners free, and collect a 
fresh stock in time for the next season in order to ensure 
having healthy parents. As Jobster hatching and oyster 
spatting both take place in summer, the pond would then 
be free from fish, and it would be a simple matter to 
arrange temporary partitions across the pond, dividing it 
into two or more compartments, one of which would be 
used for the berried lobsters and another for oysters and 
collecting tiles. It is, perhaps, unnecessary to go further 
* The Scottish Fishery Board aim at having 2,500 adult plaice in their 
spawning pond this season. 
