How to make a JQ script that will replace the css class on links in which there are only img images?

Question

JavaScript

There are such lines of code that remove the css class on all links on the page
and the code that initializes the display of images through the gallery script.

$(document).ready(function(){
$('a').toggleClass('highslide').toggleClass('lalo');
$().fancybox({
  selector : '#gg99 a:visible',
  thumbs   : {
    autoStart : true
  }
});

How can I change it so that it searches and sets the css class not for all links, but only for those that wrap the img tag?
Ie Here is the code.
selector : '#gg99 a:visible

The gallery used is this one