instances of the basal end of
the peduncle of _Conchoderma aurita_, being sunk into the skin of
Cetacea; in the same way the point of the peduncle in the male of Ibla,
is generally deeply embedded in the sack of the female. I believe in all
these cases, the cementing substance affects and injures the corium or
true skin of the animal on which the creature is parasitic, whilst the
surrounding parts, being not injured, continue to grow upwards, thus
causing the partial embedment of the Cirripede. In the case of Anelasma,
we have growth at the end of the peduncle, and consequently downward
pressure, and this may possibly cause absorption to take place in the
skin of the shark at the spot pressed on.

[21] I am informed by Mr. L. Reeve that _Pollicipes mitella_ is
eaten on the coast of China; and Ellis states ('Phil. Trans.,'
1758) that this is the case with _P. cornucopia_ on the shores of
Brittany. It is well known that the gigantic _Balanus psittacus_
on the Chilian coast, is sought after as a delicacy; and I am
assured, by Mr. Cuming, that it deserves its reputation.

_Geological History._--Having treated this subject at length, in the
volume of the Palaeontographical Society for 1851, I will not here enter
on it: I will only remark, that the Lepadidae or Pedunculated Cirripedes
are much more ancient, according to our present state of knowledge, than
the Balanidae. The former seem to have been at their culminant point
during the Cretaceous Period, when many species of Scalpellum and
Pollicipes, and a singular new genus, Loricula, existed; Pollicipes is
the oldest genus, having been found in the Lower Oolite, and, perhaps,
even in the Lias. The fossil species do not appear to have differed
widely from existing forms.

_Genus_--LEPAS. Plate I.

LEPAS. _Linnaeus._[22] Systema Naturae, 1767.

ANATIFA. _Brugiere._[23] Encyclop. Method. (des Vers), 1789.

ANATIFERA. (_Lister_) et plerumque Auctorum Anglicorum.

PENTALASMIS. (_Hill._) _Leach._ Journal de Physique, July, 1817.

PENTALEPAS. _De Blainville._ Dict. des Sci. Nat., 1824.

DOSIMA. _J. E. Gray._ Annals of Philosophy, vol. x, 1825.

[22] Linnaeus, as is well known, included under this genus both
the pedunculated and sessile Cirripedes. According to the rules
of the British Association, the name Lepas must be retained for
part of the genus; and as the sessile division was named Balanus,
by Lister and Hill, even b