ANNELIDA. 87 



rocks, stones, and shells, and even sea-weeds, 

 either in deep water or between tide-marks, and 

 others are free; while some, which do not form 

 proper tubes, burrow in the soft mud at low- water- 

 mark. A great number of the Cephalana rove 

 freely about the littoral algse and rocks, searching 

 for prey, and multitudes of the more minute kinds 

 may always be obtained by plucking up tufts of 

 the common Coralline from low-water-mark, and 

 placing them in a vase of sea-water, when the 

 worms will crawl up the sides of the glass. Many 

 kinds burrow in sand, and are to be found only by 

 digging ; and others, as the Sea-mouse, are inha- 

 bitants of the deep, and are brought up by the 

 dredge. 



Identification. — The points which require special 

 attention in the study of these animals are the 

 following : — The presence, number, and position of 

 sucking-disks ; the existence of bristles ; the lateral 

 warts called "feet," which usually carry these 

 organs ; their form ; the relative size and position 

 of the " cirri" or soft processes (usually more or 

 less resembling threads) which spring from the 

 feet ; the gills (branchiae), their shape, position, and 

 arrangement ; the presence of overlapping shields 

 along the back ; the thread-like horns or processes 

 of the head (antennae or tentacles) ; the furniture 

 of the mouth ; the existence of a protrusile pro- 

 boscis ; the jaws, hooks, knobs, or other hard parts 

 with which it is armed ; the presence or absence of 

 a tube as a dwelling, its composition, and its 

 figure. 



Authorities. — In the arrangement of the Class 

 I have been mainly guided by M. Milne-Edwards, 

 in the last edition of Lamarck's " Animaux sans 



