Drupal 6: Passing values to menu items when using drupal_get_form

I need to pass the wildcard at the end of this URL to the function accountant_registry_form which is generating a form being retrieved by drupal_get_form. I want to use the wildcard to populate the form with that registry's data as default values.

Here's the menu item's code:

  $items['accountant/edit/registry/%'] = array(
    'type'             => MENU_CALLBACK,
    'title'            => 'Create Registry',
    'page callback'    => 'drupal_get_form',
    'page arguments'   => array('accountant_registry_form',3),
    'access callback'  => 'user_access',
    'access arguments' => array('accountant create registry'),
  ); 

Here is a var_dump of the arguments passed to accountant_registry_form when I goto the URL accountant/edit/registry/5:

array(3) { ["storage"]=>  NULL ["submitted"]=>  bool(false) ["post"]=>  array(0) { } }