BAENACLES; THEIE FACTS AND THEIR FICTIONS. 
391 
holding the various divisions of the valve together decays very 
easily. The oldest known (pedunculated) Cirripede is a PoU 
licijpes, found in the Stonesfield slate — Lower Oolite — but the 
Lepadidce were not at their culminant point until during the 
deposition of the great Cretaceous system, at which time there 
were three genera, and at least thirty-two species of this group. 
No true sessile Cirripede has been found in any secondary for- 
mation.! This group first makes its appearance in Eocene 
deposits, and is found subsequently, often abundantly, in the 
later Tertiary formations. The present, however, is the epoch 
of the Balanidce, for “ these Cirripedes,” as Darwin remarks, 
“ now abound so under every zone, all over the world, that the 
present period will hereafter apparently have as good a claim 
to be called the age of Cirripedes, as the Paloeozoic period has 
to be called the age of Trilobites.” 
As mythology has almost crowded out commonplace natural 
history, there remains but scanty space at our disposal for the 
barest resume of the anatomy of the Girripedia. 
Let us take a common ship-barnacle {Lepas') as a type. Here 
we notice a fiesh-coloured, translucent, wrinkled stem, possibly 
more than a foot long, attached maybe to wood or cork, and 
from this stem there dangles a triangular pearly shell-fish, the 
valves of which, bordered with the most lovely orange, from 
time to time open and disclose several pairs of curling feelers^ 
The animal, in fact, bears no distant resemblance to a siphonate 
mollusc (see The Anatomy of the River Mussel, Popular 
Science Eeview, July 1870), which has altered its mode of 
life, and, careless of the stoppage of its ventilating flues, has 
settled down at the wrong end. Such superficial resemblance 
did not fail to mislead even men such as Linnaeus, Cuvier, and 
the classical malacologist, Poli, all of whom classed this animal 
among the Mollusca. Each valve of the shell will be seen 
superficially to be made up of two unequal, irregularly trian- 
gular parts, the larger of which, lying nearest to the stem, 
or peduncle, is termed scutum, while the other, occupying 
the free apex of the valve, is known by the name of tergum. 
There remains a single unpaired sill, to which these twin 
* Aptychus (or Trigonellites) of D’Orbigny, apart from structural differ- 
ences, is not a Cirripede. It existed at tbe Carboniferous period — ‘‘ a period 
vastly anterior to the oldest known TollicipesV 
t The form Verruca (Cretaceous), which must be ranked as a distinct 
family of equal value with Balanidce and Lepadidce, is not a real excep- 
tion. “ On the contrary, it harmonises with the law that there is some rela- 
tion between serial affinities of animals and their first appearance on this 
earth.” 
