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="Herndon1.png" />
  </query-continue>
  <query>
    <pages>
      <page ns="6" title="File:Coarse Gold1.png" missing="" />
      <page ns="6" title="File:Coarse Gold Photo1.jpg" missing="" />
      <page ns="6" title="File:Coarse Gold Photo2.jpg" missing="" />
      <page ns="6" title="File:Dairyland1.png" missing="" />
      <page ns="6" title="File:Firebaugh1.png" missing="" />
      <page ns="6" title="File:Firebaugh Photo1.jpg" missing="" />
      <page ns="6" title="File:Friant1.png" missing="" />
      <page ns="6" title="File:Friant Photo1.jpg" missing="" />
      <page ns="6" title="File:Friant Photo2.jpg" missing="" />
      <page ns="6" title="File:Herdon1.png" missing="">
        <duplicatefiles>
          <df name="Herndon1.png" user="Shannon" timestamp="2010-03-10T18:06:32Z" />
        </duplicatefiles>
      </page>
    </pages>
  </query>
</api>