yi) 
It consists of three portions, two moderately large 
masses on the lateral margins of the cephalo-thorax, 
just behind the antennules, and a median, smaller one, in 
front of the base of the mouth. The lateral portions are 
connected with the median by a duct. The median por- 
tion gives off a duct, which passes posteriorly along the 
cesophagus and enters the cecum at the anterior end of 
the stomach. When the parasite is first removed from the 
fish the digestive gland is usually of a dark brown colour, 
but after starving for a few weeks it becomes colourless. 
The product of the gland is a pale, yellow fluid, which 
can be seen as it passes along the duct between the lateral 
and median portions. 
Situated between the first and second pairs ot thoracic 
feet is a pair of glands visible in the lying animal as 
brown spots. A minute duct passes downward and then 
forward along the stomach. The duct appears to enter 
the stomach near the posterior end. 
The food of this parasite is said to be mucus, and blood 
has not been detected in the stomach.* This fact gives 
some cause for the opinion advanced by many Zoologists 
that Lepeophtheirus and other allied genera are therefore 
not parasites in the strict sense of the term, and may not 
be hurtful to their hosts. There is considerable difficulty 
in settling the question of their true food. Specimens 
taken direct from the living fish and placed under the 
microscope, rarely show even the faintest trace of red 
colouring matter in the alimentary canal. The difference in 
structure between the Caligide and the obviously blood- 
sucking Lernez is very great. This will be pointed out 
in the section dealing with Lernea branchialis, and may 
account for the apparent absence of blood. Mucus at the 
best is a poor food, but Lepeophtheirus can live for upwards 
* They do not hesitate, however, to eat their comrades when these 
become feeble. 
