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="Conclusion" />
  </query-continue>
  <query>
    <pages>
      <page ns="10" title="Template:Bathing Your Chinchilla Cat" missing="" />
      <page ns="10" title="Template:Be gentle" missing="" />
      <page ns="10" title="Template:Before bringing a Chinchilla cat home, you should prepare your living space to ensure their safety and comfort." missing="" />
      <page ns="10" title="Template:Beneficial for their urinary tract health" missing="" />
      <page ns="10" title="Template:Caring for a Chinchilla cat is a commitment" missing="" />
      <page ns="10" title="Template:Cat-specific" missing="" />
      <page ns="10" title="Template:Chinchilla cat" missing="" />
      <page ns="10" title="Template:Chinchilla cats are known for their sweet, gentle, and affectionate nature." missing="" />
      <page ns="10" title="Template:Clean and tidy" missing="" />
      <page ns="10" title="Template:Common Health Issues" missing="" />
    </pages>
  </query>
</api>