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="20160315165140" timestamp="2016-03-15T16:51:40Z" ns="0" title="Numéro" />
        <page value="20160315165716" timestamp="2016-03-15T16:57:16Z" ns="0" title="Série" />
        <page value="20160315165842" timestamp="2016-03-15T16:58:42Z" ns="0" title="Pages" />
        <page value="20160315170811" timestamp="2016-03-15T17:08:11Z" ns="0" title="Début parution" />
        <page value="20160315170952" timestamp="2016-03-15T17:09:52Z" ns="0" title="Fin parution" />
        <page value="20160315171632" timestamp="2016-03-15T17:16:32Z" ns="0" title="Date de parution" />
        <page value="20160315172118" timestamp="2016-03-15T17:21:18Z" ns="0" title="Titre (Généralités)" />
        <page value="20160315172241" timestamp="2016-03-15T17:22:41Z" ns="0" title="Titre (Détails)" />
        <page value="20160315180424" timestamp="2016-03-15T18:04:24Z" ns="0" title="Type de numéro" />
        <page value="20160315182122" timestamp="2016-03-15T18:21:22Z" ns="0" title="Nombre total de numéros" />
      </results>
    </querypage>
  </query>
</api>