This slide shows a another cross section through the body of a common earthworm (Lumbricus terrestris).  Note the eight chitinous setae (pointed to by blue arrows) that are found in each segment of the earthworm except the first and last. These structures are used to help anchor the worm when burrowing and moving through the soil.  Although each seta in the living worm does project through the body wall, this section does not reveal this fact.