Is there a way to include scrol bar in list?

Is there a way to include scrol bar in list?

this is my list code but i want when list drop down menu open , then it
must be open with scroll bar because may bi my list very long so please
help me.?
<li style="margin-top:0%;"><a id="sign"
href="index.php?main_page=shopping_cart" ><img
src="/includes/templates/pure_orange/images/cart_full.png" height=22px
width=40px;/><?php echo $count;?><span id="arrow1"
class="nav-down-arrow nav-sprite"></span></a>
<ul>
<div id="clr" style=" border-top:solid; padding-right:15px;
border-top-color:black; padding-bottom:10%; margin-top:1%;
background-color:#EDEDED; ">
<?php
// print_r($var);
for($i=0; $i<$count; $i++)
{
//$i=0;
$p_id=$var[$i]['id'];
$arr=explode(':', $p_id);
$pr_id= $arr[0];
$urii=$db->Execute("select uri from zen_ceon_uri_mappings where
associated_db_id=$pr_id");
$link=$urii->fields['uri'];
echo "<a style='margin-top:1px;' href= '$link'>"?><?php echo
$var[$i]['name'];"</a>";
}
?>
<a href="index.php?main_page=shopping_cart"
class="myButton">View Cart Item: <?php echo $count;?></a>
</ul>
</li>