Eurantia. ANNELIDA. Eurantia. 295 
The calcareous tubes in which others dwell, are secreted 
by a collar surrounding the first segment of the body. 
■ — {Siebold.) 
Reproduction takes place partly by a transverse 
fissuration, and partly by a sexual apparatus. Those 
species which undergo the process of division never 
possess genital organs at the time it is taking place ; 
but after this process ceases genital organs are deve- 
loped, and reproduction takes place by eggs. “ The 
extreme vulnerability and reproductive power of many 
Cheetopodes give rise to their frequent multiplication by 
artificial and accidental division. The fragments thus 
produced are finally developed, and the mutilated animal 
ultimately regains its lost parts. Some have tlie power 
of voluntary division from the least handling of their 
body, and these separated parts are probably developed 
to new individuals.” — {Siebold.) 
Most of the species have separate sexes, but in the 
Leeches and Earth-worms the two are always united 
in the same individual. In by far the greater number 
of the Annelides (those which have the body provided 
with bristles as organs of locomotion), the young undergo 
a complete metamorphosis. The embryo, immediately 
it escapes from the egg, swims freely about like an 
infusorial animalcule, by means of the ciliated mem- 
brane which covers its whole body. This disappears, 
the embryo lengthens, eyes appear upon the anterior 
extremity, the body becomes divided into segments, 
and bristles, &c., make their appearance. 
The Annelides vary considerably in their manner of 
life, and this, along with the structure of their breath- 
ing apparatus, has induced MM. Audouin and Milne 
Edwards to divide them into four orders : — 
I. Errantia, those in which the respiratory organs 
are attached to the dorsal surface of the body along the 
whole or greater part of its length, hence called Dorsi- 
brancliiata by Cuvier and others. These species are 
found living a free and wandering life, crawling actively 
in mud or swimming in the water. 
II. Tuhicola or Sedentaria, those in which the 
respiratory organs are formed like plumes, attached to 
the head or anterior portion of the body, hence called 
by many authors Capitohranchiata. These species 
live a sedentary life, and are found, with few exceptions, 
having their abode in tubes. 
III. Terricola or Earth-worms, those in which the 
respiratory organs are internal, being in the form of 
small vesicles opening externally by very minute pores. 
These are found making their dwelling-place in soft 
earth, piercing the ground in all directions. 
IV. Suctoria or Suckers, those in which the respira- 
torj' organs are internal, like the preceding order, and 
disposed in the form of small membranous sacs, each 
of which communicates externally by a minute orifice 
on the ventral aspect of the body. They possess no 
bristles, but are provided with suctorial discs by which 
they progress. These are all natives of the water, and 
many are found living partially as parasites upon fishes. 
Order I. — EURANTIA {=.Dorsibranchiata). 
All the species belonging to this order are aquatic, 
crawling with activity in the mud or swimming with 
facility in the water. The body in some of them is 
very long and slender — some species in the equatorial 
seas attaining the length of five feet — in others broad 
and rather short. Their head is distinct from the 
trunk, and is furnished with two pairs of rudimentary 
eyes, a certain number of conical or filiform appendages 
which are distinguished into antennae, palpi, and ten- 
tacles, and a mouth furnished with a proboscis whicli 
can be protruded at will, and often armed with strong 
horny jaws. The body is composed of numerous 
narrow segments or rings, varying in number from 
twenty to five hundred. In the majority of the species 
each segment or ring has on each side an organ which 
many naturalists call a foot. It is in the form of a 
fleshy tubercle ; is composed of two divisions placed one 
above the other called rami, or branches ; and provided 
with one or two brushes of bristles. These bristles are 
of two kinds, subulate and hooked, and the animal can 
protrude them considerably by means of muscles appro- 
priated to that use. In addition to these bundles of 
bristles, there are attached to these feet a number of 
soft and blunt appendages, called cirrhi. They are 
usually two to each foot, but their number and position 
vary considerably. They are either in the form of long, 
subulate, fleshy tentacles, or merely compressed leaflets 
or papillary tubercles. In general they are partially 
contractile. The gills or branchiae vary much in form, 
number, and position. In some the organ assumes the 
form of arbuscles or tufts, or fan-shaped crests ; in a 
second series it is a simple or pectinated filament; and 
in a third it is a nipple-like lobe, or merely a mem- 
branous tubercle. In general they are placed along 
the back, but sometimes they are arranged along the 
sides or at the tail. 
“ Organized for locomotion,” says Dr. Johnston, 
“ this tribe of Annelides — the tyrants or the aristocracy 
of their race — wander abroad, and are in constant war- 
fare with all around them. They crawl on the surface 
at a pace that varies in the species from extreme slow- 
ness to energetic activity. Many of them swim with 
ease, and others burrow in the wet sand of the shore. 
They are eminently carnivorous, with the exception 
perhaps of the Ariciidce, which may be geodephagous 
or feeders on putrescent matter.” Some of them appear 
to be truly pelagian, and are only met with in the high 
seas; but the great majority dwell between tide-marks 
on the shore, where they find refuge and concealment 
under stones, or among corallines and sea-weeds. A 
small number burrow in the sand, in which they form 
a sort of sheath by a glairy secretion from the skin, 
and a few are truly tubiculous ; but these sheaths arc 
not indispensable, and can be occasionally abandoned 
without inconvenience. The mouth, as has been 
stated, is well adapted for their rapacious manner of 
life ; but in addition to these organs of offence, these 
animals are likewise provided with organs of defence 
against their enemies. The principal ones are the 
bristles with which the segments of their body are pro- 
vided. Some Annelidans when alarmed, such as the 
Aphrodites, instinctively contract the body into a sort 
of ball, bringing the head and tail into near contact, 
and in this manner seem anxious to elude the danger. 
Others, that have a long vermiform body, wriggle and 
