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>
    <alllinks galcontinue="Boros_Charm|718" />
  </query-continue>
  <query>
    <pages>
      <page pageid="226" ns="0" title="Signal Pest" />
      <page pageid="251" ns="0" title="Celestial Archon" />
      <page pageid="294" ns="0" title="Erebos&#039;s Emissary" />
      <page pageid="298" ns="0" title="Heliod&#039;s Emissary" />
      <page pageid="300" ns="0" title="Observant Alseid" />
      <page pageid="429" ns="0" title="Cavern Lampad" />
      <page pageid="650" ns="0" title="Azorius Charm" />
      <page pageid="714" ns="0" title="Golgari Charm" />
      <page pageid="716" ns="0" title="Gruul Charm" />
      <page pageid="746" ns="0" title="Boon Satyr" />
    </pages>
  </query>
</api>