48 TRANSACTIONS. LIVERPOOL BIOLOGICAL SOCIETY. 
solely by the weight of the waste water from the tanks 
filling the tipping box which periodically empties. It 
has proved, as the result of six years’ working, to be very 
effective in hatching such sea-fish as the plaice; and is 
also suitable for maintaining the “ berried ” adult lobsters 
and the newly hatched young in a healthy condition. At 
other times of the year, when not required for fish, the 
hatching tanks have been used on occasions for keeping 
Fic, 9. The hatching tanks when used for rearing lobsters 
in summer. 
invertebrata such as Ilydroids, Polyzoa, Mchinoderms, 
Tunicata and Mollusca 1a a healthy condition temporarily 
while under observation or while awaiting investigation. 
This mechanism would probably also be well adapted for 
rearing experiments with delicate invertebrates which 
require some vertical movement in the water; and, in 
fact, will be found to be useful in biological stations in 
general apart from fish-hatcheries, 
