Segments of an annelid. Refs: 
<dl><dd><cite class="book" style="font-style:normal">Ruppert, E.E., Fox, R.S., and Barnes, R.D. (2004) "Annelida" in    <i> Invertebrate Zoology</i> (7<sup>th</sup> ed.), Brooks / Cole, pp. 414  <small><a href="https://en.wikipedia.org/wiki/International_Standard_Book_Number" class="extiw" title="en:International Standard Book Number">ISBN</a>:  <a href="//commons.wikimedia.org/wiki/Special:BookSources/0030259827" title="Special:BookSources/0030259827">0030259827</a>. </small></cite> (fig 13-1)</dd>
<dd><cite class="book" style="font-style:normal">Rouse, G. (1998) "The Annelida and their close relatives" in Anderson, D.T. , ed.   <i> Invertebrate Zoology</i>, Oxford University Press, pp. 178  <small><a href="https://en.wikipedia.org/wiki/International_Standard_Book_Number" class="extiw" title="en:International Standard Book Number">ISBN</a>:  <a href="//commons.wikimedia.org/wiki/Special:BookSources/0195513681" title="Special:BookSources/0195513681">0195513681</a>. </small></cite> (fig 8.2 a).</dd>
<dt>Key</dt>
<dd></dd></dl><ul><li><span style="background-color:#CCf; border:solid 1px black">   Prostomium  </span></li>
<li><span style="background-color:#ff0; border:solid 1px black">   Peristomium</span></li>
<li><span style="font-weight:bold; color:#f00">O</span> Mouth </li>
<li><span style="background-color:#0f0; border:solid 1px black">   Growth zone </span></li>
<li><span style="background-color:#CCC; border:solid 1px black">   Pygidium</span></li>
<li><span style="font-weight:bold; color:#840">O</span> Anus</li></ul>
<a href="https://en.wikipedia.org/wiki/User:Philcha" class="extiw" title="en:User:Philcha">Philcha</a> (<a href="https://en.wikipedia.org/wiki/User_talk:Philcha" class="extiw" title="en:User talk:Philcha">talk</a>)
2009-03-29
<span class="int-own-work" lang="en">Own work</span> (<span lang="en" dir="ltr">Original text: <i><bdi lang="">I created this work entirely by myself.</bdi></i></span>)