Display Titles Under Thumbnails with WP Default Gallery System

I’m using the default wordpress gallery system to do client proof photo galleries. Here’s an example:

http://www.lincolnbarbour.com/clientlogin/archive/or-coast/
password: beach

It works great, but I can’t figure out how to get the titles (filenames) to appear underneath the thumbnail.

Can someone help me out with the code or template file?

Thanks!