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>
    <allpages apcontinue="Liste_des_catégories" />
  </query-continue>
  <query>
    <allpages>
      <p pageid="891" ns="0" title="Baguage Merle à plastron" />
      <p pageid="985" ns="0" title="Bulgrane rampante, observation du 2018/06/23 (Terril 14 (5 d&#039;Auchel)) - 1" />
      <p pageid="604" ns="0" title="CCCO" />
      <p pageid="221" ns="0" title="Calendrier" />
      <p pageid="494" ns="0" title="Catégories" />
      <p pageid="736" ns="0" title="Circulation motorisée, observation du 2014/02/19 (Terril 98 (Estevelles)) - 1" />
      <p pageid="758" ns="0" title="Circulation motorisée, observation du 2014/03/23 (Terril 116-117 (10 de Oignies)) - 1" />
      <p pageid="956" ns="0" title="Couleuvre" />
      <p pageid="989" ns="0" title="How Good Is Kona Coffee" />
      <p pageid="609" ns="0" title="Lestrem Nature" />
    </allpages>
  </query>
</api>