The spine on the labrum
becomes reduced in size. In this way the animal gradually approaches the
Prawn-form, in which the median eye has become indistinct, the spine of
the labrum, and the outer branches of the cheliferous and ambulatory
feet have been lost, the mandibular palpi and the abdominal feet have
acquired distinct joints and setae, and the branchiae come into action.
In another Prawn, the various larval states of which may be easily
recognised as belonging to the same series by the presence of a
dark-yellow, sharply-defined spot surrounding the median eye, the
youngest Zoea (Figure 32), probably produced from the Nauplius, agrees
in all essential particulars with the species just described; its
further development is, however, very different, especially in that
neither the feet of the middle, nor those of the hind-body are formed
simultaneously, and that a stage of development comparable to Mysis in
the number and structure of the limbs does not occur.
(FIGURE 32. Youngest (observed) Zoea of another Prawn. The minute buds
of the third pair of maxillipedes are visible. The formation of the
abdominal segments has commenced. Paired eyes still wanting. Magnified
45 diam.)
Traces of the outer maxillipedes make their appearance betimes. Then
feet appear upon four segments of the middle-body, and these are
biramose on the three anterior segments, and simple, the inner branch
being deficient, on the fourth segment.
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