Balanid^. ANNELIDA. Annklida. 
the whole world, the greater number however inhabit- 
ing the warmer, temperate, and tropical seas. The 
name of harnacle shell was originally given to the 
genus Lepas, which may be known by the head or 
capitulum being compressed and composed of five 
approximate valves. They derive this name from its 
being at one time believed that they gave origin to tlie 
barnacle goose ! 
Family II. — BALANID.® (Sessile Cirripcds, or 
Sea-acorns). 
The Balanidce are characterized by tbeir being 
fixed to submarine bodies without the intervention of 
a peduncle. The body of the animal is inclosed in a 
cylindrical or bell-shaped tube open at the top, formed 
of several valves united together, side by side, by a 
dentated suture, and covered by what is called an 
operculum, which consists generally of four valves 
nearly equal-sized and sunk into a flexible skin, 
allowing them a considerable degree of motion. The 
base bj' which they are fixed is a shelly plate. The 
species are numerous and most widely diffused, taking 
possession of rocks, ships, timber floating or at 
rest, shells of Crustacea and Mollusca, &c. Some of 
them are of considerable size, and one species of 
the genus Balanus (B. psittaceus) found on the coast 
of Chili, growing to the size of five or six inches, 
forms a very common and highly esteemed food for 
the natives, who call \tpico. The flesh is said to equal 
in richness and delicacy that of the crab. Another 
species, B. tintinndbulum (fig. 200), is equally prized by 
Balauus Tiutinnabulum. 
the Chinese, the flesh of which is said to resemble the 
lobster. Some of the species, as in Acasta, are found 
attached to sponges, while others, as in Pyrgoma, are 
embedded in corals. The species of the genus Corormla 
and Tubicinella, attach themselves to the bodies of 
whales; and as they increase in size their shells are 
proportionally enlarged by the addition of new matter 
to the base of the valves, and they gradually raise 
themselves out of the substauce of the skin in which 
they are immersed. 
Class — ANNELIDA (Annelides, or Red Worms). 
The class Annelida, as now constituted, is composed 
of a series of animals which form only a small part of 
the great heterogeneous class Vermes, or Worms, of 
Linuseus. They are distinguished, however, from all 
other worms by the fact that they possess red or 
coloured blood, and hence are ofteri called by the name 
of Red Worms. This peculiarity was considered of 
such importance by Cuvier that he placed them in his 
last edition of the “ Regne Animal” at the head of the 
sub-kingdom Articuluta. Their general appearance 
nevertheless seems to point them out as the represen- 
tatives of the larval rather than the perfect state of 
insects, and thus to indicate their proper position to be 
below both Insects and Crustacea. 
Annelides. then, are worms with red or coloured 
blood, circulating in a double S 3 'stem of complex vessels, 
with a nervous system consisting of a double central 
cord, and I’espiring by organs which are either developed 
externally or are spread over the sirface of the skin, or 
concealed internalljL The body, (vhich is more or less 
elongated, is always divided into numerous rings 
(annuli), from which circumstance the whole class 
derives its name. The first of these rings contains the 
mouth and the principal organs of sense. It is called 
the head, but in outward appearance scarcely differs 
from the rest, which all agree in having the same form 
and nearly the same size throughout. None of the 
Annelides are possessed of true feet or articulated limbs, 
but the greater number of them are provided with 
hairs or hooks, or bundles, of bristles which supply their 
place, while others have a suctorial disc which serves 
them for progression. Their antennai (when they 
possess them) are seldom jointed, and the organs of 
their mouth consist of jaws, more or less powerful, or 
of a simple tube. The epidermis or external skin is 
very thin, and is not ciliated except where it covers the 
external branchiie. The sense of touch is chiefly deve- 
loped at the two first rings of the body, and exists either 
in form of a tentacular proboscis, contractile antennae, 
or processes of variable number and shape called cirrhi. 
In a great many of the Annelides the eyes are wanting ; 
in some they are represented by black dots merely, or 
eye-specks, which in the leeches and some others are 
numerous, and are considered to be light-perceiving 
organs. The digestive canal is usually straight, rarely 
having convolutions. 
The skin in many of the species secretes a quantity 
of mucus which covers the bod}’, and by means of which 
some of them glue together pieces of shell, grains of 
sand, &c., so as to form a tube to lodge themselves in. 
