Instead, you want to select :lt(), for example:
$('ul.more_stories li').hide();
$('ul.more_stories li:lt(3)').show();
Or, a little easier / faster using .slice():
$('ul.more_stories li').hide().slice(0, 2).show();
This approach hides them all and then uses the same set and displays index elements 0-2.
, 3, :
$('ul.more_stories li:gt(2)').hide();
, .slice():
$('ul.more_stories li').slice(3).hide();
, <ul>, .each(), :
$('ul.more_stories').each(function() {
$(this).children().slice(3).hide();
});