FQ 
poda. There is an incomplete articulation near the 
middle. At the apex of the abdomen there are two short 
papille known as the furca or caudal stylets, which 
usually have four or five plumose hairs on their posterior 
margins. 
There are twelve pairs of appendages* (Plate IT., fig. 1) 
as follows: —One pair of antennules, one pair of antenne, 
one pair of mandibles, two pairs of maxille, two pairs of 
maxillipedes, and five pairs of feet, the first three pairs of 
feet only being adapted for swimming. 
The eyes appear as a reddish spot in the living animal, 
and are situated on the dorsal surface mid-way between 
the frontal margin and the transverse line of the cephalo- 
thorax. When this spot is examined microscopically 
(Plate III., fig. 13) it is found to consist of two lateral 
eyes closely approximated, embedded in a mass of reddish- 
black pigment, and wholly under the carapace. Hach eye 
has a simple, spherical, crystalline lens, beneath a thin 
cornea. Behind the lens is a row of retinal cells of fairly 
large size, lined internally with a tapetum or pigment 
layer. A chitin division lined with deep red pigment 
separates the two eyes. The earlier Zoologists had con- 
siderable doubt as to the true position of the eyes, some 
even believed the animals were’ blind. Others 
mistook the semi-circular suckers on the frontal margin 
of Caligus already referred to for the organs of vision, 
giving them the name “ Binoculus.”’ 
The antennules are placed at the external margin, just 
behind the suture on the frontal plate, and each consists 
of two joints. The basal joint is much larger than the 
apical, and is clothed on its upper margin with plumose 
sete. 
* The minute details of the jointing and sete of the appendages are not 
shown in these figures. 
