96 
Two to four specimens have been found after examining 
numerous catches of young cod of one dozen each. The 
ratio thus varies from one in three fish to one in six. In 
one or two instances two and sometimes three specimens 
were found on young cod eight inches long. The length 
of a full grown female Lernwa is a little over one inch. 
The adult female is securely fastened to its host by 
strong branched horns, three in number, which are buried 
in the tissues of various parts of the gill arches. In 
many instances the head was found to have actually 
penetrated the ventral aorta. To obtain the specimens 
in an entire condition the tissues of the host have to be 
carefully dissected. Attempts to remove them by force 
always result in the head being left in the fish. The 
parasite, when once fixed, remains in the same position 
throughout life. When it dies the softer parts decay, but 
the head continues for a long time embedded in the tissues 
of the host, and is often met with there when dissecting 
out lving specimens. 
EXTERNAL CHARACTERS. 
The adult female (Plate IV., fig. 1) is cylindrical. It 
is unsegmented, but roughly divided into three parts—a 
globular head with anchor-like processes, connected by a 
narrow neck to a much swollen posterior part. 
The globular head corresponds to part of the cephalo- 
thorax in Lepeophtheirus. It is furnished with three 
more or less branched horns, two lateral and one median 
and dorsal. The head is shghtly curved downwards, ter- 
minating in a conical apex. 
The anterior portion of the neck represents the 
remainder of the cephalo-thorax and the fourth thoracic 
segment. The whole of the neck is marked by fine trans- 
verse lines. 
