You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <querypage qpoffset="10" />
  </query-continue>
  <query>
    <querypage name="Ancientpages">
      <results>
        <page value="20120906034425" timestamp="2012-09-06T03:44:25Z" ns="0" title="Manuscrito 230 BNC" />
        <page value="20120916193423" timestamp="2012-09-16T19:34:23Z" ns="0" title="Manuscrito 230 BNC/fol 17v" />
        <page value="20120916231758" timestamp="2012-09-16T23:17:58Z" ns="0" title="Manuscrito 230 BNC/fol 18r" />
        <page value="20120917002437" timestamp="2012-09-17T00:24:37Z" ns="0" title="Manuscrito 230 BNC/fol 19r" />
        <page value="20120917005735" timestamp="2012-09-17T00:57:35Z" ns="0" title="Manuscrito 230 BNC/fol 19v" />
        <page value="20120917134339" timestamp="2012-09-17T13:43:39Z" ns="0" title="Manuscrito 230 BNC/fol 20r" />
        <page value="20120918034158" timestamp="2012-09-18T03:41:58Z" ns="0" title="Manuscrito 230 BNC/fol 20v" />
        <page value="20120918151545" timestamp="2012-09-18T15:15:45Z" ns="0" title="Manuscrito 230 BNC/fol 18v" />
        <page value="20120918163302" timestamp="2012-09-18T16:33:02Z" ns="0" title="Manuscrito 230 BNC/fol 21r" />
        <page value="20120918195241" timestamp="2012-09-18T19:52:41Z" ns="0" title="Manuscrito 230 BNC/fol 21v" />
      </results>
    </querypage>
  </query>
</api>