It is, however, to be particularly remarked, that the development of the
sexual peculiarities does not stand still on the attainment of sexual
maturity.
(FIGURE 50. Foot of the second pair ("second pair of gnathopoda") of the
male of Orchestia Tucurauna, magnified 15 diam.
FIGURE 51. Foot of the second pair ("second pair of gnathopoda") of the
female of Orchestia Tucurauna, magnified 15 diam.)
For example, the younger sexually mature males of Orchestia Tucurauna,
n. sp., have slender inferior antennae, with the joints of the flagellum
not fused together, the clasping margin ("palm," Sp. Bate) of the hand
in the second pair of feet is uniformly convex, the last pair of feet is
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.
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