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>
    <pages>
      <page pageid="689" ns="0" title="IVRAF FA 0162 : Les baobabs cimetières dans la culture Sérère" />
      <page pageid="690" ns="0" title="IVRFA FO 150 Rites de fécondité et folklore chez les Kagnaleng à Toubacouta" />
      <page pageid="740" ns="0" title="Sokone" />
    </pages>
  </query>
</api>