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="318416" ns="0" title="Euthyrisellidae" />
      <page pageid="176770" ns="0" title="Amorbia emigratella" />
      <page pageid="162298" ns="0" title="Orthotrichum undulatifolium" />
      <page pageid="189150" ns="0" title="Phtheochroa" />
      <page pageid="88881" ns="0" title="Similipedia" />
      <page pageid="375557" ns="0" title="Neoclinus">
        <images>
          <im ns="6" title="File:Sarcastic fringehead in plastic tube.JPG" />
        </images>
      </page>
      <page pageid="474262" ns="0" title="Guernea sombati" />
      <page pageid="356608" ns="0" title="Gerarus teutonicus" />
      <page pageid="233217" ns="0" title="Nothoploca nigripunctata zolotarenkoi" />
      <page pageid="303320" ns="0" title="Fridericia cuneifolia" />
    </pages>
  </query>
</api>