Text on Login form

I want to change the text on the log in form - 'the Not a member yet? Join now blurb'  but for the life of me I can't figure out where to find that file.

If anyone knows, I would appreciate the help

Thank

yoursite.com/administration/lang_file.php

Look for

type in  join now click on apply

it should return the search results

_login_form_description2join (System) edit

Thank you :)