If it be desired to form a notion of what our parasite may have looked
like when half way in its progress from the one form to the other, we
may consult the figures given by Darwin, (Lepadidae Plate 4 figures 1 to
7) of Anelasma squalicola. This Lepadide, which lives upon Sharks in the
North Sea, seems, in fact, to be in the best way to lose its cirri and
buccal organs in the same manner. The widely-cleft, shell-less test is
supported upon a thick peduncle, which is immersed in the skin of the
Shark. The surface of the peduncle is beset with much-ramified, hollow
filaments, which "penetrate the Shark's flesh like roots" (Darwin).
Darwin looked in vain for cement-glands and cement. It seems to me
hardly doubtful, that the ramified hollow filaments are themselves
nothing but the cement-ducts converted into nutritive roots, and that it
is just in consequence of the development of this new source of
nourishment, that the cirri and buccal organs are in the highest degree
aborted. All the parts of the mouth are extremely minute; the palpi and
exterior maxillae have almost disappeared; the cirri are thick,
inarticulate, and destitute of bristles; and the muscles both of the
mouth and cirri are without transverse striation. Darwin found the
stomach perfectly empty in the animal examined by him.

...

Having reached the Nauplius, the extreme outpost of the class, retiring
furthest into the gray mist of primitive time, we naturally look round
us to see whether ways may not be descried thence towards other
bordering regions. By the structure of the abdomen in Nauplius we might
be reminded, like Oscar Schmidt, of the moveable caudal fork of the
Rotatoria, which many regard as near allies of the Crustacea, or at any
rate of the Arthropoda; in the six feet surrounding the mouth we might