child of post type (custom)

You can display child pages of particular parent foo page using following code ( using parent page ID ):

$the_query = new WP_Query( 'post_type=foo&post_parent=93' );

// The Loop
while ( $the_query->have_posts() ) :
$the_query->the_post();
echo '<li>' . get_the_title() . '</li>';
endwhile;