76 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
will probably be agreed that 11 is unlikely that, with the 
large, varied and irregularly scattered population that 
we find the sea to contain, two nets should often catch the 
same quantities of the same sets of organisms. Con- 
sequently, a result like that obtained on April 22nd, where 
the two nets caught precisely the same amounts and where 
the lists of organisms constituting the hauls are almost 
exactly alike both im kinds and numbers, is interesting. 
On considering the Diatom list, some other points 
come out:—The average number of Diatoms per catch 
often varies considerably from day to day. ‘Thus on 
April 5th the average of all catches of that day was 
3,933,800, while on April 6th it fell to 548,750; on April 
24th it was 191,873, while on April 25th it was only 665. 
But these numbers scarcely give an adequate idea of 
the quantitative variation among individual catches. 
Thus on September 10th surface-nets . and B contained 
250 and 550 respectively while two days later the corres- 
ponding numbers were 15,495,500 and 16,500,500; on 
April 8th two hauls of the Nansen net gave respectively 
198,000 and 3,739,000, and many other such cases could 
be quoted. 
Turning now to the Diatom hauls within Port Erin 
Bay, a general inspection of an unsmoothed curve drawn 
from them shows the well-marked maximum at the end 
of March and earlier part of April (fig. 17). The marked 
increase of Diatoms, and also of Copepod Naupli, is seen 
well in the following three surface hauls : — 
March 26. March 27. March 29, 
WA xe. ONC: Lea eece 
Total Diatoms = 220,000 ... 277,000 ... 326,000 
Biddulphia mobiliensis ... 46,000 ... 50,000 ... 58,000 
Chaetoceros debile... .... 6,000 ..: 8,000 2 aiGaaie 
« decipiens ... 100,000 ... 150,000 ... 160,000 
Coseinodisecus concinnus ... 64,000 ... 67,000 ages 
Copepod nauplii... .. 4,000 °.2. 27,000" ST ieaSo0en 
