68 Lamarck’s Genera of Shells. 
CLASS IX. 
ANNULATA*. 
Animal soft, elongated, vermicular, naked or inhabiting tubes : 
the body furnished either with segments or transverse wrinkles ; 
often destitute of head, eyes and antenne ; no articulated feet, 
but in their stead, in most, retractile bristly mammillee disposed 
in lateral rows. Mouth subterminal, either simple, orbicular, or 
labiate, or proboscis-shaped, and often furnished with jaws. 
Medulla longitudinal, knotty; nerves of sense and motion; 
red blood cireulating in veins and arteries; respiration per- 
formed by internal or external branchic; branchice sometimes 
unknown. 
This class comprehends three orders : 
1. Aunulata, without feet. 
2. Annulata, with Antenne. 
3. Sedentary Annulata. 
The two first orders have no testaceous covering, and con- 
sequently do not fall under our present notice. We begin 
therefore with the 
Third Order. 
SEDENTARY ANNULATA. 
Animal always inhabits a tube, which it never entirely quits, 
and has noeyes. Branchiz always at, or near to, one of the ex- 
tremities of the body, unless the tube have a lateral opening, 
through its whole length. The tubes either membranous or 
horny, more or less incrusted externally with grains of sand and 
fragments of shell; or solid, calcareous and homogeneous. 
They are generally attached to marine substances. 
The Sedentary Annulata are divided into four families, 
Dorsalia, Maldania, Amphitritea, and Serpulea. 
Dorsatiat. (2 Genera). 
1. Arenicola—has no shell. 
2. Siliquariaf. 
Body tubular, unknown. 
* From annulus, a ring, or segment. 
+ From dorsum, the back, because the branchie are ranged along it. 
+ From siliqua,a bean-pod. 
