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="Crafting|257" />
  </query-continue>
  <query>
    <pages>
      <page pageid="40" ns="0" title="Red Hexorium Crystal" />
      <page pageid="86" ns="0" title="Green Hexorium Crystal" />
      <page pageid="87" ns="0" title="Blue Hexorium Crystal" />
      <page pageid="88" ns="0" title="White Hexorium Crystal" />
      <page pageid="92" ns="0" title="Black Hexorium Crystal" />
      <page pageid="249" ns="0" title="White Hexorium Wafer" />
      <page pageid="253" ns="0" title="Black Hexorium Wafer" />
      <page pageid="254" ns="0" title="Hexorium Coprocessor" />
      <page pageid="255" ns="0" title="Hexorium Processor" />
      <page pageid="256" ns="0" title="Rainbow Energized Globule" />
    </pages>
  </query>
</api>