SCALE- WOEM. 165 



account for it ; the edge and point of each bristle being 

 intended to act upon the surface of the object above it, 

 beneath which it is forcing its way. 



A secondary pencil of bristles also issues from the 

 upper side of each of these tubercular sheaths, so as to 

 project diagonally upwards and outwards beneath the 

 edge of the shield-leaf. This pencil consists of between 

 thirty and forty bristles, which are connected with a 

 cartilaginous rod exactly similar to that of the primary 

 bundle. These bristles run off to a very fine point, and 

 each one is marked on both sides with serratures so 

 delicate as to be only just discernible with a magnifying 

 power of 300 diameters. There are thus about 270 

 movable bristles of exquisite structure in each segment, 

 which multiplied by 36, the number of segments in the 

 body, gives a total of 9720 distinct organs of motion 

 possessed by this animal, besides the broad leaf-like 

 shields, which perhaps may act as fins, and the short 

 tentacular feet, one of which is placed beneath the pri- 

 mary bristle-sheath, on each side of the segment. 



By dissection after death, I have found the proboscis 

 in the form of a long oval sac, very muscular and firm, 

 of a blackish hue, lying in the anterior part of the body, 

 which, on being cut open, showed four horny teeth 

 placed in its neck so as to meet each other in the 

 centre. I have never seen the protrusion of this organ 



