SEA-FISHERIES LABORATORY. 979 
(half a million late in April, and nearly one million in 
May). 
Guinardia, like Rhizosolenia, has its maximum in 
June (nearly nine millions on June 11th). It is absent 
in August and most of September, making a shght and 
short-lived reappearance at the end of that month and 
then dying off for the winter. 
Lauderia.—The single species L. borealis is rare 
until April, then rapidly attains to a maximum of 20 
millions on April 22nd, diminishes in May and June, is 
rare throughout the summer, and has a smaller second 
maximum at the end of September and in October. 
The Indo-Pacific Diatom Biddulphia sinensis, which 
has appeared recently in our N.W. European seas, is 
again present at Port Erin in November in quantity. 
It seems now, from its appearance in the 
gatherings, to be in much more vigorous condition than 
when it first occurred in the Irish Sea. The cells are 
seen to be in active division, and chains of two and four 
cells adhering together are quite frequently seen. 
The above lists of the chief Diatoms show very 
clearly the marked Diatom minimum in August. From 
about August 12th to 23rd Diatoms were practically 
absent, then they reappeared and. increased rapidly to 
form the second maximum early in October. 
APRIL, JUNE AND SEPTEMBER DIATOMS. 
If we make out curves for the catches in the bay 
taken with the fine nets only—the nets that catch the 
bulk of the Diatoms at the times when they are most 
abundant—we find that in all four years after the April 
maximum there is a drop in at least the early part of 
May, and then more or less of a rise either later in May 
or in June; and this secondary rise, like the primary 
one in April, is mainly due to Diatoms, but to quite a 

