This diagram shows a transverse section of dero. c., caelom; c.l., cells of the so-called "lateral line"; d.m., dermo-muscular wall including muscles and skin; d.v., dorsal blood vessel; ect, ectoderm; ent, entoderm; g, gut; g.f., giant nerve fibers; gl, glandular cells assisting in digestion; m.c., circular muscle fibers; m.l., longitudinal muscle fibers; n, nephridium; n.v., ventral nerve chain, made up of nerve cells and nerve fibers; s, setae; v.v., ventral blood vessel.

Annelid

This diagram shows a transverse section of dero. c., caelom; c.l., cells of the so-called "lateral line";…