L ^os ] 



The Distribution of Marine Plankton. 



In order to endeavour to co-ordinate the work of the many naturalists 

 who make use of the tow-net round the coasts of the British Isles 

 during the year, the following circular has been issued. The list of 

 organisms, upon the presence or absence of which information is 

 desired, contains only such as can be quite easily recognised. The 

 scheme must be regarded as more or less experimental for this year, 

 with a view to findinfr out what can be done in this direction. 



Jllnvinc i3iolor(ical dissociation of tfjc ©Iniicti Ixingtiom. 



The Laboratory, Plymouth, 

 December 30th, 1S96. 



Sir, — Many of tlie organisms commonly found in the plankton of the sea 

 around the Dritish coast exhibit remarkable variations in their relative 

 abundance at particular localities from year to year, but little is known as 

 to the extent and causes of such variations. As a number of naturalists 

 make use of the tow-net at many places round the coast, especially during 

 the summer, much valuable information would be obtained if in all cases 

 records were kept of the presence or absence of a limited number of the 

 commoner species, and these records subsequently brought together. 



In the hope that you may be willing to assist in obtaining such information, 

 I enclose a short list of organisms, the presence or absence of which I would 

 ask you to record at any locality and as often as you may be using the 

 tow-net during the year 1897. The records may Ije forwarded to me from 

 time to time, and all should be sent in before January 31st, 1898. 



Additional copies of the list will be sent, if desired, and your assistance 

 is requested in inducing other naturalists to co-operate in making the records. 



I am, Sir, yours faithfully, 



E. J. Allen, 



Director. 



