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verse section. It is composed of five distinct parts—an 
oval cephalo-thorax, three thoracic, and one terminal 
segment, representing the genital segment and abdomen. 
The anterior portion of the genital segment in the female 
is indistinctly divided into eleven joints. 
The cephalo-thorax attains its greatest width just 
behind the eyes; beyond that point the sides converge 
until they reach the first thoracic segment. The cephalo- 
thorax is produced anteriorly into a broad blunt rostrum. 
In the very early cyclops stage (Plate IV., fig. 3), the 
rostrum is further produced into a short triangular 
filament which secures the parasite to its host. 
The eyes (Plate V., fig. 3) are situated on the dorsal 
surface a short distance behind the rostrum. In the 
living animal they appear as a dark red spot with a 
crystalline lens projecting slightly at each side. When 
examined microscopically the structure is found to be the 
same as that described in Lepeophtheirus. A thin cornea 
encloses a spherical crystalline lens. Behind the lens a 
row of fairly large retinal cells is lined internally with a 
tapetum layer. A chitinous septum lined with deep red 
pigment separates the two eyes. The appendages attached 
to the cephalo-thorax are as follows : — 
The antennules are placed at the posterior angles of the 
lateral margins of the rostrum. They are short, and are 
composed of four nearly equal joints furnished with fine 
sete. 
The antenne are composed of two joints. The apical 
joint is provided with a strong claw on its external angle. 
The antenne usually project beyond the rostrum, and it 
is by means of these that the attachment to the host is 
maintained when the filament is broken off. 
The mandibles are not enclosed in the suctorial mouth. 
They are situated at the base of the lateral surfaces of the 
