5 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
pipes has given me much concern during the year. he 
tubes of the former and the byssus fibres of the latter 
occasionally become detached and are carried along by 
the stream of water until a tap is reached, and the supply 
of water to the tank below is obstructed. The calcareous 
sponge, Leucosolenta botryoides, now grows in quantity 
on the walls of,certain of the tanks. 
Fic. 12. The spawning ponds. 
Considerable difficulty was experienced during the 
autumn of 1907 in collecting adult plaice for spawning 
purposes. Of the 220 which supplied all the eggs hatched 
this year 190 were caught in our own trammel nets, the 
remainder being added by the Assistant Curator while 
on a trip in Mr. R. Knox’s steam trawler “ Lady Loch.” 
All these fish were maintained in a healthy condition 
throughout the winter, and it is satisfactory to record 
that, in spite of a high percentage of unfertilised eggs, 
