of six weeks in filtered sea water without visible food of 
any kind. 
From the large numbers of flounders examined in the 
Piel laboratory, partly in connection with this memoir, 
but chiefly in connection with fisheries work, during the 
past year or two, the conclusion has been arrived at, that 
Lepeophtheirus pectoralis to some extent feeds on blood, 
and may be hurtful to the fish, especially when present 
in numbers (see figure on p. 68). 
The appendages are more suited for a sedentary life 
than even a semi-pelagic one. ‘The animals can only 
remain swimming for short periods, and their presence in 
tow-nettings, therefore, is accidental. They do not, under 
normal conditions, and as long as the fish remains in a 
healthy state, leave their host. In the fish tanks at Piel 
over 150 flounders, all more or less infested with 
Lepeophtheirus, are kept during the spawning season. 
The waste water from the tanks is carefully filtered for 
periods of at least three months in the spring, to collect 
the eggs shed by the fish. Yet not even one specimen of 
the parasite has been found in the filter. When the 
fish are examined and the parasites removed, no matter 
how carefully, the skin, especially where there are a 
number close together, is usually lacerated and bleeding. 
The males and immature females on the general surface 
of the body do not seem to remain long enough in one 
place to cause obvious injuries. Under the fins, however, 
and on the fins themselves, where the egg-bearing females 
are usually found, and where they le for weeks in the 
same position if not disturbed, is the part of the fish 
chiefly injured. The pectoral fin in some instances may 
be partially destroyed, and pieces of the tissues are fre- 
quently found enclosed in the second maxillipedes of the 
parasite. 
