130 ANNELIDES. SEDENTABLE. 



tached to the head or anterior part of the body, and generally 

 inhabiting tubes. 2. Dorsibranchice, where the branchiae are 

 towards the middle of the body or along the sides. 3. Abran- 

 MCE, where the branchiae are not apparent externally. La- 

 marck, on the other hand, divides the class into three orders from 

 other considerations, viz. 

 Order I. SEDENTARLE. Destitute of antennae, eyes, and jaws, 



and inhabiting tubes. 

 Order II. ANTENNAT^E. Head with antennae and eyes, and a 



protractile proboscis often armed with jaws. 

 Order III. APODES. Destitute of feet or setiferous papillae 



and antennated head. 



ORDER L SEDENTARIJE. 



Animal inhabiting a tube, from which it never entirely departs; 

 no eyes ; branchiae at one of the extremities of the body. 



The animals of this order are constantly inclosed in sheaths or tubes, from which 

 they never depart, and which are almost always closed on the sides. These tubes 

 are either membranaceous or horny, more or less incrusted exteriorly with grains of 

 sand and fragments of shells, or solid, calcareous, and homogeneous. The animal 

 inhabitant is elongated, vermiform, with the sides of the body furnished with bun- 

 dles of subulate bristles, in general very short, and hooked bristles to enable it to 

 move in the tube, to which it is not attached. Lamarck divides this order in the 

 following manner : 



1. Branchiae so far as known, disposed at or near one of the extremities. 



a. Branchias in general known, and disposed at or near the anterior part of the body. 



* Branchiae separate or covered by an operculum ; tube solid and calcareous. Ser- 

 pulacea. 



** Branchias neither separate nor covered by an operculum. Amphitritcea. 



b. Branchiae indeterminate, supposed at the posterior part of the body ; tube open 

 at both ends. Maldanice. 



2. Branchiae dorsal, or disposed along the body. Dm'salice, 



FAMILY I. SERPULACEA. 



Branchiae separate or covered by an operculum ; tube solid and 

 calcareous. 



The animals of this family have no tentacula, eyes, or jaws. Their body is fur- 

 nished on the sides with setiferous papillae and with hooked retractile bristles. The 

 tube which they inhabit is always solid, calcareous, open at its anterior extremity, and 

 fixed on marine bodies. It is generally irregularly bent or spiral, attenuated towards 

 the base, and has sometimes the interior cavity divided posteriorly into unequal cells. 



Gen. 1. MAGTLUS, Lam. 



Shell with the base bent into a spiral form, oval, with four con- 

 tiguous convex whorls, of which the last is the largest, and 

 prolonged into a straight waved tube; tube convex above, ca- 



