106 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



spasmodic and may occur at any time no matter what the 

 temperature of the water may be. One point that most 

 writers are agreed upon is that during the summer months, 

 and with high temperatures of the sea, the specimens captured 

 are all small. In the winter months when the sea temperature 

 is low the specimens are mostly of large size. That is very 

 much what we find in the Irish Sea. The summer-caught 

 Pleurobrachia rarely exceed 8 millimetres in height. Many 

 of the specimens collected during the invasion in December 

 were 22 millimetres high. 



