but as far as I know from all other Crustacea, by the circumstance that
structures which are elsewhere combined with the two anterior limbs
(antennae), here occur separated from them.

The anterior antennae of the Copepoda, Cladocera, Phyllopoda (Leydig,
Claus), Ostracoda (at least the Cypridinae), Diastylidae, Edriophthalma,
and Podophthalma, with few exceptions relating to terrestrial animals or
parasites, bear peculiar filaments which I have already repeatedly
mentioned as "olfactory filaments." A pair of similar filaments spring,
in the larvae of the Cirripedia and Rhizocephala, directly from the
brain.

(FIGURE 56. Nauplius of Sacculina purpurea, shortly before the second
moult, magnified 180 diam. We may recognise in the first pair of feet
the future adherent feet, and in the abdomen six pairs of natatory feet
with long setae.)

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"