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>
    <alltransclusions gatcontinue="BasicBox2|9887" />
  </query-continue>
  <query>
    <pages>
      <page pageid="1" ns="0" title="Main Page" />
      <page pageid="133" ns="2" title="User:Scott/Sandbox" />
      <page pageid="6896" ns="0" title="Sandbox" />
      <page pageid="9870" ns="0" title="Null Crystal Fragment" />
      <page pageid="9872" ns="0" title="Null Crystal Shard" />
      <page pageid="9873" ns="0" title="Small Null Crystal" />
      <page pageid="9881" ns="0" title="Medium Null Crystal" />
      <page pageid="9882" ns="0" title="Large Null Crystal" />
      <page pageid="10174" ns="0" title="Puncuation Posse" />
    </pages>
  </query>
</api>