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="Bértola_Nora" />
  </query-continue>
  <query>
    <pages>
      <page ns="0" title="B 8.8.1" missing="" />
      <page ns="0" title="B 8.8.1." missing="" />
      <page ns="0" title="Beatriz Soria" missing="" />
      <page ns="0" title="Bentos, Plancton y biofilms, Cuenca del Salado, Ciclos Biogeoquimicos, Ecología de peces, Ecología de insectos, Entomología, Herpetología" missing="" />
      <page ns="0" title="Benítez Guillermo" missing="" />
      <page ns="0" title="Betina Corsico" missing="" />
      <page ns="0" title="Biología-varios campos" missing="" />
      <page pageid="1358" ns="0" title="Balsalobre Agustín" />
      <page pageid="945" ns="0" title="Barone Vicente" />
      <page pageid="1452" ns="0" title="Bosio gabriela" />
    </pages>
  </query>
</api>