rks._--This genus is intimately related, as has been
remarked by Professor Macgillivray,[36] to Lepas: if we look to the body
of the animal, which from being less exposed to external influences
must, in the Cirripedia, offer the most trustworthy characters, we find
that in Conchoderma there are additional filamentary appendages attached
to the cirri, that there are no caudal appendages, that the teeth of the
mandibles are finely pectinated, and that the ovarian tubes run higher
up round the sack; in every other respect, there is the closest
similarity, even to the arrangement of the bristles on the cirri. In the
capitulum, the difference consists chiefly, though not exclusively, in
the less development of the valves, and their consequent wide
separation: the scuta, however, in Conchoderma, are added to beneath
their umbones, or original centres of growth, which is never the case,
or only to a very slight degree, in Lepas. Conchoderma has no very close
affinity to any other genus. As the majority of authors have ranked the
two common species under two distinct genera (Otion and Cineras), I may
observe, that there is no good ground for this separation; in the above
few specified points in which Conchoderma differs from the genus most
closely allied to it, the two species essentially agree together. If we
take the nearest varieties of _C. virgata_ and _C. aurita_, there is but
a very slight difference even in the form of their valves, and these
hold the same relative positions to each other; the carina, however, is
always less developed in _C. aurita_; even the colouring in both tends
to follow the same arrangement. The only obvious distinction between the
two species, are the ear-like appendages of _C. aurita_, which, however,
are not developed in its early age, are subject to considerable
variation, are of no high functional signification, and are indicated in
_C. virgata_ by two prominences on the same exact spots. On these
grounds I conclude, that the generic separation of the two species is
quite inadmissible.

[36] Remarks on the Cirripedia, &c.; 'Edin. New Phil. Journal,'
vol. xxxix, p. 171.

1. CONCHODERMA AURITA. Pl. III, fig. 4.

LEPAS AURITA. _Linn._[37] Systema Naturae, 1767.

OTION CUVIERANUS (!) BLAINVILLIANUS (!) BELLIANUS (!)
DUMERILLIANUS (!) RISSOANUS. _Leach._ Encyclop. Brit., vol.
iii, Supp., 1824, and Zoological Journal, vol. ii, p. 208,
July 1825.

OTION DEP