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>
    <allpages>
      <p pageid="111" ns="0" title="Blood on the Beach" />
      <p pageid="13" ns="0" title="Bobby Krupczak" />
      <p pageid="59" ns="0" title="Book club" />
      <p pageid="62" ns="0" title="Book summer 2007" />
      <p pageid="48" ns="0" title="Brandon Summer 2007" />
      <p pageid="92" ns="0" title="Bunco" />
      <p pageid="20" ns="0" title="Cartographer" />
      <p pageid="150" ns="0" title="Cartographer Agent Build Instructions" />
      <p pageid="122" ns="0" title="Cartographer Agent Installation" />
      <p pageid="227" ns="0" title="Cartographer FAQ" />
    </allpages>
  </query>
  <query-continue>
    <allpages apcontinue="Cartographer_GUI_Installation" />
  </query-continue>
</api>