The same may be observed in Cerapus
and Caprella, and probably in all cases where hereditary sexual
differences occur.
(FIGURE 52. Male of a Bodotria, magnified 10 diam. Note the long
inferior antennae, which are closely applied to the body, and of which
the apex is visible beneath the caudal appendages.)
Next to the extensive sections of the Stalk-eyed and Sessile-eyed
Crustacea, but more nearly allied to the former than to the latter,
comes the remarkable family of the Diastylidae or Cumacea. The young,
which Kroyer took out of the brood-pouch of the female, and which
attained one-fourth of the length of their mother, resembled the adult
animals almost in all parts. Whether, as in Mysis and Ligia, a
transformation occurs within the brood-pouch, which is constructed in
the same way as in Mysis, is not known.* (* A trustworthy English
Naturalist, Goodsir, described the brood-pouch and eggs of Cuma as early
as 1843. Kroyer, whose painstaking care and conscientiousness is
recognised with wonder by every one who has met him on a common field of
work, confirmed Goodsir's statements in 1846, and, as above mentioned,
took out of the brood-pouch embryos advanced in development and
resembling their parents. By this the question whether the Diastylidae
are full-grown animals or larvae, is completely and for ever set at
rest, and only the famous names of Agassiz, Dana and Milne-Edwards, who
would recently reduce them again to larvae (see Van Beneden, 'Rech.
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