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="El_extrano_caso_del_Dr_Jekyll_y_Mr_Hyde" />
  </query-continue>
  <query>
    <pages>
      <page ns="0" title="Carlos Ruiz Zafón" missing="" />
      <page ns="0" title="Claudia Piñeiro" missing="" />
      <page pageid="176" ns="0" title="Campos de fresa" />
      <page pageid="37" ns="0" title="Carlos Ruíz Zafón" />
      <page pageid="41" ns="0" title="Don Quijote de La Mancha (resumen largo)" />
      <page pageid="31" ns="0" title="Dulce Chacón" />
      <page pageid="64" ns="0" title="Eduardo Galeano" />
      <page pageid="222" ns="0" title="El Abuelo La Cesta Y El Mar" />
      <page pageid="48" ns="0" title="El Dador de Recuerdos" />
      <page pageid="85" ns="0" title="El cazador del desierto" />
    </pages>
  </query>
</api>