Among the males of these various
Bopyridae, that of Entoniscus Porcellanae occupies the lowest place; it
is confined all its life to six pairs of feet, which are reduced to
shapeless rounded lumps.
The Amphipoda are distinguishable from the Isopoda at an early period in
the egg by the different position of the embryo, the hinder extremity of
which is bent downwards. In all the animals of this order which have
been examined for it,* (* In the genera Orchestoidea, Orchestia,
Allorchestes, Montagua, Batea n.g., Amphilochus, Atylus, Microdeutopus,
Leucothoe, Melita, Gammarus (according to Meissner and La Valette),
Amphithoe, Cerapus, Cyrtophium, Corophium, Dulichia, Protella and
Caprella.) a peculiar structure makes its appearance very early on the
anterior part of the back, by which the embryo is attached to the "inner
egg-membrane," and which has been called the "micropylar apparatus," but
improperly as it seems to me.* (* Little as a name may actually affect
the facts, we ought certainly to confine the name "micropyle" to canals
of the egg-membrane, which serve for the entrance of the semen. But the
outer egg-membrane passes over the "micropylar apparatus" of the
Amphipoda without any perforation, according to Meissner's and La
Valette's own statements; it appears never to be present before
fecundation, attains its greatest development at a subsequent period of
the ovular life, and the delicate canals which penetrate it do not even
seem to be always present, indeed it seems to belong to the embryo
rather than to the egg-membrane.
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