42 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



Lewis, we find that 168 collections of the surface plankton 

 in Port Erin Bay were made with the usual coarse and fine 

 tow-nets during the ten months — January to the end of 

 October, 1914. If we combine the volume of the catch 

 of the coarse and fine nets and regard the result as a fairly 

 accurate representation of the amount of pelagic life present at 

 the time the hauls were made, we are able to give the following 

 summary of the distribution throughout the period mentioned. 

 The amount of plankton present in the Bay in January and 

 February was very small. The average volume for eight 

 hauls in January was 2-5 c.c. Seven hauls in February gave 

 an average of 3-2 c.c. March showed a distinct increase 

 with an average of 6-5 c.c. for eight hauls. In April there 

 was a further marked increase, rising to 24 c.c. at the middle 

 of the month and ending with 70 c.c. on April 30th: the 

 average for nine hauls was 34-7 c.c. The first collection with 

 the coarse and fine nets in May was taken on the 4th, 

 when the combined volume of the two hauls was 88-5 c.c, 

 the maximum quantity collected during 1914. Three days 

 later it fell to 61-5 c.c. The plankton was found to have 

 still further diminished on May 12th, and the volume of the 

 catch made by the two nets then amounted to 26-2 c.c. : the 

 average for eight hauls during May was 34-8 c.c. In June, 

 although there was one large haul of 41 c.c. on the 11th, the 

 average for nine collections was only 24-5 c.c. The amount 

 taken by the two nets at the beginning of July was 21-2 c.c, 

 at the end of the month it had decreased to 4-5 c.c, and the 

 average for nine hauls was 12-7 c.c There was a slight 

 increase at the beginning of August compared with the 

 conditions at the end of July, but this was not maintained. 

 The quantity present during the last two weeks of the month 

 fell from 11-3 c.c. to 2-6 c.c, and the average for nine hauls 

 was 10-8 c.c. September also commenced with an increase 

 compared with the end of the previous month. The volume 

 diminished towards the middle of the month to 4-4 c.c It 



