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>
    <allimages gaicontinue="1917_1921.png" />
  </query-continue>
  <query>
    <pages>
      <page pageid="65" ns="6" title="File:1.png" />
      <page pageid="215" ns="6" title="File:12.png" />
      <page pageid="216" ns="6" title="File:13.png" />
      <page pageid="271" ns="6" title="File:1807 1810.png" />
      <page pageid="281" ns="6" title="File:1843 1846.png" />
      <page pageid="277" ns="6" title="File:184450.gif" />
      <page pageid="272" ns="6" title="File:1844 1848.png" />
      <page pageid="282" ns="6" title="File:1906 1910.png" />
      <page pageid="278" ns="6" title="File:190703.gif" />
      <page pageid="279" ns="6" title="File:191718.gif" />
    </pages>
  </query>
</api>