ARTICULATA. 99 



the genus Clymene^ the body is long and cylindrical, the extremities abrupt, 

 the segments few and dissimilar, the head distinct, the thoracic portion long, 

 and the abdomen short. The thoracic feet have two branches. It forms a 

 tube with small shells and sand. 



Order 2. Doesibranchia. Here the organs of motion, and especially 

 those of respiration, are arranged in linear series, either from end to end, or 

 at the middle portion of the body. The head and eyes are usually distinct, 

 and there are antennte, jaws, and an extensible rostrum. The families are 

 arranged by Audouin and Milne Edwards as follows : 1, Aphroditidce j 2, 

 Amphinoimdod ; Z^ Emiicidce ; ^i^ NereidcB ', ^. AriciidcB ; Q. Peripatidce ; 

 T, Chetopteridce j 8, Arenicolidoi. 



Fain. 1. Apkromitidce. Body generally depressed, and shorter and 

 wider than in the other annelida. Back with two rows of large membrana- 

 ceous scales or elytra (except in the genus Palmyra)., beneath which are 

 the branchice, which are not well developed. Two pairs of jaws are generally 

 present, and the elytra and superior cirri are alternately present and absent 

 upon the segments to a certain extent. A'phrodite has thirteen pairs of 

 elytra, three antennae. The jaws are cartilaginous or rudimentary. Several 

 species rival the humming birds in the brilliancy and play of their colors. 

 A. acideata {pi. 77, ^g. 16), of the European seas, attains a length of six 

 inches, and the dorsal scales are hidden by a hairy covering. 



Pam. 2. AmphinomidcB. Segments similar, branchiae ramose, tufted, or 

 plumose, well developed, dorsal, or at the base of the feet ; head distinct, 

 month unarmed, no aciculi, feet with one or two branches. 



Fa'.n. 3. Eimicidce. The rostrum has from seven to nine corneous jaws ; 

 branchite wanting or well developed, in the form of pectinated filaments ; 

 feet aciculate. Eunice has two eyes, seven strong jaws, four upon the left 

 and three upon the right side ; five large tentacles above the mouth, and two 

 smaller ones at the nape ; branchiae pectinated upon one side of the support- 

 ing branch. The body is long and sub-cylindrical, the segments sometimes 

 numbering four hundred. This genus.contains the largest species of annel- 

 ida known, E. gigantea of the Antilles, which is four feet or more in length. 



Earn. 4. Nereidix. In this family the jaws are either absent, or amounting 

 to two or four ; the rostrum extends considerably beyond the head ; antennae 

 mostly well developed. Nereis is a genus of worms found upon the coast, 

 moving about freely, or hidden in the cavities of rocks, or in dead shells ; and 

 sometimes sunk in the mud. Like many other annelida, it is used by fisher- 

 men as bait. Some are of a considerable size, and the colors are often agree- 

 able. PJiyllodoce {pi. 77., jig. 11) belongs to this family. The place of Spio 

 filicornis {fig. 14), which has two very long antenna?, is not ascertained. 



Earn. 5. Ariciida;. Head and rostrum distinct ; antennae, eyes, and 

 branchiae wanting, or rudimentary ; jaws and tentacular cirri absent ; each 

 foot with a single cirrus. 



Earn 6. Peripatidcc. This family contains the single genus Peripatus 

 of Guilding, who observed it in the West Indies, and described it as a 

 mollusc. The body is somewhat limaciform, both ends obtuse, the annula- 

 tions not very distinct, each side margined with a row of short, thick, 



303 



