n the
Balanidae, of five longitudinal bundles of voluntary muscles, with
transverse striae, fixed to the scuta and terga, and giving them powers
of independent movement. In the Lepadidae, the lower valves, or when such
are absent, the membranous walls of the capitulum, move with the scuta
and terga when opened or shut; and the lower part of the capitulum is
separated by a moveable peduncle from the surface of attachment; in the
sessile Cirripedes, the lower valves are firmly united together into an
immovable ring, fixed immovably on the surface of attachment. I will not
compare the softer parts, such as the cirri and trophi, of the Lepadidae
with those of the Balanidae, as my examination of this latter family is
not fully completed: I will only remark, that there is a very close
general resemblance, more especially with the sub-family Chthamalinae.

_Geographical Range; Habitats._--The Pedunculated Cirripedes extend over
the whole world; and most of the individual species have large ranges,
more especially, as might have been expected, those attached to floating
objects; excepting these latter, the greater number inhabit the warmer
temperate, and tropical seas. Of those attached to fixed objects, or to
littoral animals, it is rare to find more than three or four species in
the same locality. On the shores of Europe I know of only three, viz., a
Scalpellum, Pollicipes, and Alepas. At Madeira (owing to the admirable
researches of the Rev. R. T. Lowe), two Paecilasmas, a Dichelaspis, and
an Oxynaspis are known. In New Zealand, there are two Pollicipes and an
Alepas, and, perhaps, a fourth form. From the Philippine Archipelago, in
the great collection made by Mr. Cuming, there are a Paecilasma, an Ibla,
a Scalpellum, Pollicipes, and Lithotrya. Of all the Lepadidae, nearly
half are attached to floating objects, or to animals which are able to
change their positions; the other half are generally attached to fixed
organic or inorganic bodies, and more frequently to the former than to
the latter. Most of the species of Scalpellum are inhabitants of deep
water; on the other hand, most of Pollicipes,[21] of Ibla, and Lithotrya
are littoral forms. The species of Lithotrya have the power of
excavating burrows in calcareous rocks, shells, and corals; and the
singular manner in which this is effected, is described under that
genus. Anelasma has its sub-globular peduncle deeply embedded in the
flesh of Northern Sharks; and I have seen