68 
examination it is possible to collect a series of these 
parasites, from the early “‘chalimus” stage to the adult 
condition, from one fish. Sometimes only a few speci- 
mens occur on the fish. At other times large numbers 
are to be found. It is by no means rare to find between 
twenty and thirty mature females under each pectoral 
fin alone, as in the case which is illustrated in the cut. One 
hundred specimens of another species, L. heppoglossi, have 
been collected from the ‘‘ white” side of a halibut in the 
Aberdeen Fish Market. The average length of a mature 
Lepeophtheirus pectoralis, 32 specimens, on the pectoral fin of a Flounder, 
from a photograph. 
ege-bearing female is one-fifth of an inch, and of a male 
one-ninth of an inch. A mature female measures about 
one-tenth of an inch at its greatest breadth, and a male 
one-twelfth of an inch. These parasites attach themselves 
to the fish by means of their powerful second maxillipedes, 
assisted by the antenne, and a decided pull has to be 
exerted before they can be torn away. By depressing 
the edges of the carapace and applying them closely to 
the skin, the parasite can increase its: holding power to 
such an extent that the posterior end can be torn from the 
