:}32 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



amount of sunshine in April and May, and possibly the 

 increase of plankton in June over '08 may be due to that 

 cause. 



This is probably the best place to show (tig. 16) the 

 weekly variations in the temperature of sea and air in 

 Port Erin Bay, as recorded at the Biological Station. For 

 comparison we give also the diagram (fig. IT) printed in 

 last Report, showing the temperature variations in '08. 

 We have not a diagram for '07, but we have the series of 

 weekly records corresponding to those of '08 and '09. It 

 will be seen that this year ('09) the air-temperature whole 

 line, in place of crossing the dotted line representing the 

 sea-temperatures at one point (tbe first week in May in 

 both '07 and '08), nearly reaches it at the end of March, 

 crosses it early in April and back again at the end of the 

 month, gets above it again in the beginning of May, and 

 dips under and up again for the last time in the middle 

 of that month. After that there is less difference between 

 the temperature of sea and air during the summer than 

 in the previous year, and the air-temperature reaches 

 58° F. only, in place of 61°, but remains above the sea 

 longer in autumn, to August 21st in place of August 5th 

 in '08. 



Vertical Hauls. 



The two vertical closing nets we have had in most 

 frequent use during the three years are called briefly the 

 " Hensen " and the " Nansen." The " Hensen " was 

 obtained from Kiel, and is a quantitative net of the same 

 size as the " Medium Apstein," but provided with two 

 brass semi-circular flaps at the mouth, so that it can be 

 closed at any depth by the action of a " messenger " sent 

 down the line. Strictly speaking, it is the " Petersen- 

 Hensen " net, but that name is too long for every-day use 



