ARTICULATA—ANNELIDES. 775 
antenna, and between them and the first segment of the body. The tenta- 
cula are either inarticulated filaments on the head or anterior part of the 
body, or papillz more or less elongated into filaments at the orifice of the 
mouth. The proboscis is fleshy and contractile, composed sometimes of one, 
and sometimes of two rings, inclosing the jaws; and the jaws are bony or 
calcareous, inclosed in the proboscis, in number at least two, and sometimes 
to the number of seven or nine. When this is the case, they are in two 
rows, one above the other. The body of the Annelides is in some naked, or. 
without hairs or bristles ; in others, furnished with bristles without papilla, 
Gr with rows of setiferous papilla. The bristles which are found without 
papillz, are not retractile, while the setiferous mamillz are generally so. 
These papille, or mamille, are fleshy sheaths, which inclose each a bundle 
of subulate bristles. The sete traverse the papille, and are attached to the 
muscles under the skin. M. Savigny gives the name of foot io each pair 
of setiferous papilla, and he divides each foot into two branches, one supe- 
rior or dorsal, and one inferior or ventral. The ventral branch is the most 
projecting, and they are best organized for progressive motion. At each 
branch are observed tubular, subaruculated, generally contractile cirri, 
analogous to antenne. These are the antenne of the body. Those of the 
dorsal branches are generally longest. The bristles of each branch, or 
the subulate bristles, are hard, stiff, opaque, and shine with metallic lustre. 
They form at each branch a moveable tuft, which the animal has the power 
of erecting. or withdrawing at.will. Besides, the subulate bristles are dis- 
tinguished from others, which are thicker, straight, conical, and very sharp, 
inclosed in a particular sheath, and generally one in each branch, those of 
the ventral branches being commonly the strongest. In some genera, how- 
ever, these acicular bristles are wanting. Some of the Annelides possess a 
third kind of bristles, which M. Savigny terms hooked bristles. These are 
flattened and armed below with sharp hooks. They are also retractile, and 
concealed in the thickness of the skin in repose. The ¢entacular cirri are those 
of the first pair of feet, and often those of the two or three following pairs, 
which are sometimes destitute cf bristles, and have only cirri. In this case, the 
cirrl acquire a greater developement, and take the appearance of tentacula. 
The last pair of feet constitute, by an analogous transformation, the two 
filaments which terminate the body posteriorly, in certain species. The first 
segment of the body, either alone or united to some of the following ones, 
often forms a ring larger than the others, more apparent than the head ; and 
in the last segment is a plicated, anal aperture, turned upwards. All the 
Annelides respire by bronchie, and live in water, mud, sand, or moist earth. 
These bronchie vary much in situation, size, and form. In some, they are 
distributed along the body, partially or wholly, and in others, they are found 
at one extremity, chiefly the anterior. The intestine is straight, generally 
contracted into rings, and the anus terminal. The organs of circulation 
consist of lateral, dorsal, and central vessels, extending the length of the 
