Directory Plugin - Category Thumbnail resize

Hi,

I want to change the thumbnail size for the listings on a Category page.

Default is 50 x 26

<div class="entry-summary">
<img width="50" height="26" src="http://www.sfvlocal.com/wp-content/uploads/2011/11/logo-150x80.png" class="alignleft wp-post-image" alt="logo" title="logo" />
</div>

I could not find where to make the change. It seems like a style change but i could not find it in the style sheets.

Thanks,

Bruce