ARTICULATA — ANNELIDES. 775 



antennae, and between them and the first segment of the body. The tenta- 

 cula are either marticulated filaments on the head or anterior part of the 

 body, or papillae 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 papillae, 

 or with rows of setiferous papillae. The bristles which are found without 

 papillae, are not retractile, while the s€tiferous mamillae are generally so. 

 These papillae, or mamillae, are fleshy sheaths, which inclose each a bundle 

 of subulate bristles. The setae traverse the papillae, and are attached to the 

 muscles under the skin. M. Savigny gives the name of foot to 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, subarticulated, generally contractile cirri, 

 analogous to antennae. These are the antennae 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 tentacular cirri are those 

 of the first pair of feet, and often those of the two or three following pairs, 

 which are sometimes destitute of bristles, and have only cirri. In this case, the 

 cirri 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 bronchiae, and live in water, mud, sand, or moist earth. 

 These bronchiae 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 extreinity, 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 



