)
At the base of the inferior antennae in the Decapoda the so-called
"green-gland" has its opening; in the Macrura at the end of a conical
process. A similar conical process with an efferent duct traversing it
is very striking in most of the Amphipoda. In the Ostracoda, Zenker
describes a gland situated in the base of the inferior antennae, and
opening at the extremity of an extraordinarily long "spine." In the
Nauplii of Cyclops and Cyclopsine, Claus finds pale "shell-glands,"
which commence in the intermediate pair of limbs (the posterior
antennae). On the other hand in the Nauplii of the Cirripedia and
Rhizocephala the "shell-glands" open at the ends of conical processes,
sometimes of most remarkable length, which spring from the angles of the
broad frontal margin, and have been interpreted sometimes as antennae
(Burmeister, Darwin) and sometimes as mere "horns of the carapace"
(Krohn). The connexion of the "shell-glands" with the frontal horns has
been recognised unmistakably in the larvae of Lepas, and indeed the
resemblance of the frontal horns with the conical processes on the
inferior antennae of the Amphipoda, is complete throughout.* (* In
connexion with this it may be mentioned that, in the females of
Brachyscelus, in which the posterior antennae are deficient, the conical
processes with the canal permeating them are nevertheless retained.
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