SEA-FISHERIES LABORATORY. 985 
NoctTILUGA. 
The Protozoon Noctiluca miliaris is very abundant 
in the coastal waters of the Irish Sea in late summer 
and autumn, and is much rarer round the Isle of Man. 
In fact, it is probable that swarms sometimes abound on 
the Welsh and Lancashire coast without reaching Manx 
waters. A few years ago, before these intensive studies 
were started, we have a record of capturing Noctiluca 
in vast quantities off the North coast of Anglesey, in 
August, at a time when none were found in the tow-nets 
used at Port Erin. At Piel, in the Barrow Channel, 
as we stated last year, Noctiluca was present in 
September, 1908, to the amount of about 2,000,000 per 
gallon. 
Its spread, during summer and autumn, on the West 
coast of England, is certainly from South to North. It 
appears first on the Welsh coast, gradually spreads 
across Liverpool Bay as the summer advances, and 
arrives in Morecambe Bay and the Barrow Channel about 
September. It does not usually extend far out to sea, 
however abundant it may be along the coast; and its 
occurrence this year in quantity round the south end 
of the Isle of Man in July is quite exceptional, and must 
have been due to some special conditions. 
In 1910, at Port Erin, with the exception of small 
numbers on two days (February Ist and March 3rd) in 
spring, Noctiluca did not appear until after the middle 
of July. It remained in fair abundance (up to 
thousands and tens of thousands per haul) until late in 
September, and then slowly diminished in quantity to 
tens and hundreds at the end of the year. It is a neritic 
organism, rare in the first half of the year, but probably 
never completely absent from our shores. The highest 
numbers in the months of 1910 when it was abundant at 
