i6 PEOCEEDIXGS OV THE 



They may show something hke double or half the quantity of 

 organisms obtained in neighbouring hauls. 



For comparison with such gatherings, we may examine the similar 

 series of hauls taken late in August from about the s^ame locality. 

 On August 21st there are practically no Diatoms present, there 

 being only a very few individuals of Blddulphia mohiliensis. On 

 the other hand, the Copepoda are much more abundant than they 

 were in April, for example, compare Oithona similis, where only 

 tens, amounting at most to a few hundreds, were present in April, 

 and thousands (reaching eleven thousand in the weighted net) were 

 in the August haul. Other interesting differences can be noticed 

 on comparing the two lists in detail. 



The Copepoda have two maxima in the year, the first in April 

 and the second in September and October. The records start in 

 January with about 2000 per haul and keep below that level 

 throughout February and most of March. During April they 

 rapidly mount up with a series of successively higher records, with 

 falls between, such as April 2nd 4,500, April 13th 10,755, 

 April 16th 11,600, till the climax is reached on April 27th with 

 29,825. During May the numbers are low, 1,015 to 6,505 ; in 

 June they rise somewhat, 13,610 on the 11th and 15,450 on the 

 27th, falling again in July to numbers between 2,895 and 7,930. 

 August shows a series of rises with falls between, the tops being 

 18,200 on the 10th, 19,400 on the 14th, 14,700 on the 15th, 

 16,915 on the 24th, and 10,970 on the 29th. September begins 

 at a low level, reaches 11,942 on the 4th, and, with falls between, 

 27,177 on the 12th, 13,440 on the 20th, and 27,312 on the 20th, 

 followed by 10,582 on 21st, 18,450 on 23rd, 11,850 on 24th, and 

 12,110 on 30th. October is also high, with 16,973 on the 9th, 

 27,790 on 14th, and 24,480 on 24th. November shows one high 

 figure, 10,937 on the 8th ; while December ranges from 1,724 to 

 2,755 ; the year's record ending very much at the same level where 

 it commenced in January. The range in number of the Copepoda 

 per net, 30 to 29,800, is considerable compared with that of some 

 groups, but does not equal that of the Diatoms. 



The monthly averages of the Copepoda during this year are as 

 follows : — 



Jan 1,816 



Feb 793 



Mar 1,379 



Apr 5,858 



July 5,462 



Aug 5,496 



Sept 6,514 



Oct 17,572 



May 3,415 i Nov 6,923 



June 12,138 1 Dec 2,289 



The highest averages here (June and October) do not quite 

 coincide with the maxima (April and September-October) in the 

 previous treatment where the days were taken singly. The ex- 

 planation is, of course, that although April contains a maximum 

 far above that of June, it also contains in the earlier part of the 

 month many low records that pull down the average when the 

 month is treated as a whole. The maxima in high average bulk of 



