In Mysis this
first larval skin may be compared to a Nauplius; in Ligia it appears
like a maggot quite destitute of appendages, but produced into a long
simple tail (Figure 37). The egg-membrane is retained longer than in
Mysis; it bursts only when the limbs of the young Slater are already
partially developed in their full number. The dorsal surface of the
Slater is united to the larval skin a little behind the head. At this
point, when the union has been dissolved a little before the change of
skin, there is a foliaceous appendage, which exists only for a short
time, and disappears before the young Slater quits the brood-pouch of
the mother.
(FIGURE 37. Maggot-like larva of Ligia, magnified 15 diam. R remains of
the egg-membrane. We see on the lower surface, from before
backwards:--the anterior and posterior antennae, the mandibles, the
anterior and posterior maxillae, maxillipedes, six ambulatory feet, the
last segment of the middle-body destitute of appendages, five abdominal
feet, and the caudal feet.)
The young animal, when it begins to take care of itself, resembles the
old ones in almost all parts, except one important difference; it
possesses only six, instead of seven pairs of ambulatory feet; and the
last segment of the middle-body is but slightly developed and destitute
of appendages. It need hardly be mentioned that the sexual peculiarities
are not yet developed, and that in the males the hand-like enlargements
of the anterior ambulatory feet and the copulatory appendages are still
deficient.
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