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="Grayson_Lake" />
  </query-continue>
  <query>
    <allpages>
      <p pageid="10" ns="0" title="Blue River" />
      <p pageid="25" ns="0" title="Cave Run Lake" />
      <p pageid="576" ns="0" title="Dale Hollow" />
      <p pageid="14" ns="0" title="Deam Lake" />
      <p pageid="19" ns="0" title="Dix River" />
      <p pageid="24" ns="0" title="Driftwood River" />
      <p pageid="13" ns="0" title="Elkhorn Creek" />
      <p pageid="3" ns="0" title="Floyds Fork" />
      <p pageid="8" ns="0" title="Fourteen Mile Creek" />
      <p pageid="578" ns="0" title="Freeman Lake" />
    </allpages>
  </query>
</api>