The form in this Nauplius-brood is
extremely various,--it is sometimes compressed laterally, sometimes
flat,--sometimes elongated, sometimes oval, sometimes round or even
broader than long, and so forth. The changes which the first larval
stages undergo during the progress of growth, consist essentially in an
extension of the body and the sprouting forth of new limbs. "The
following stage already displays a fourth pair of extremities, the
future maxillae." Then follow at once three new pairs of limbs (the
maxillipedes and the two anterior pairs of natatory feet). The larva
still continues like a Nauplius, as the three anterior pairs of limbs
represent rowing feet; at the next moult it is converted into the
youngest Cyclops-like state, when it resembles the adult animal in the
structure of the antennae and buccal organs, although the number of
limbs and body segments is still much less, for only the rudiments of
the third and fourth pairs of natatory feet have made their appearance
in the form of cushions fringed with setae, and the body consists of the
oval cephalothorax, the second, third, and fourth thoracic segments, and
an elongated terminal joint. In the Cyclopidae the posterior antennae
have lost their secondary branch, and the mandibles have completely
thrown off the previously existing natatory feet, whilst in the other
families these appendages persist, more or less altered.
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