SEA-FISHERIES LABORATORY. 1} 
These three somewhat diverse samples were obtained, 
it will be noticed, within a period of ten days, in July, 
from localities not ten miles apart. 
We add, also, for comparison, the similar quantita- 
tive record of three characteristic gatherings made in 
the centre of the Irish Sea, off the West coast of the 
Isle of Man, near Port Erin, as follows :— 
(D) a typical phyto-plankton, taken in April 
haul (100 c.c.). 
(E) a typical scanty zoo-plankton, from August 
beso Gees). 
(F) a mixed gathering, mainly phyto-plankton, in 
September, when the autumnal Diatoms are 
a large 

present in quantities (11 c.c.). 
Finally, we show in 
(G) a typical phyto-plankton gathering from the 
Hebridean Sea, near Hyskeir, North of Mull, 
for comparison with p and F. 
It will be noticed, on comparing the Loch Ranza 
plankton with the Irish Sea hauls in April and 
September, that in species present, and their abundance, 
the Scottish July gathering is much more like the 
September than the April phyto-plankton; for example, 
in both July (c) and September (F) the most abundant 
form is Rhizosolenia semispina, a species rarely present 
and never abundant in April. But, as has been pointed 
out above, the phyto-plankton gatherings North of Mull 
(column G) show resemblances to the vernal rather than 
to the autumnal phyto-plankton of the Irish Sea, 
although to some extent combining their characters and 
differing from both. 
Several possibilities occur as an explanation of this 
curious difference between the summer planktons in the 
Hebridean and the Irish Sea, respectively. 
