slender and similar to the preceding. Subsequently the antennae become
thickened, two, three, or four of the first joints of the flagellum are
fused together, the palm of the hand acquires a deep emargination near
its inferior angle, and the intermediate joints of the last pair of feet
become swelled into a considerable incrassation. No museum-zoologist
would hesitate about fabricating two distinct species, if the oldest and
youngest sexually mature males were sent to him without the uniting
intermediate forms. In the younger males of Orchestia Tucuratinga,
although the microscopic examination of their testes showed that they
were already sexually mature, the emargination of the clasping margin of
the hand (represented in Figure 50) and the corresponding process of the
finger, are still entirely wanting. 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