finding the last span in DOM with a particular classname
===

     <div class="comments_container clearfix">
     <hr />
	<ul class="comment_struct">
			
	      <li class="commenter_pic">
		<img src="images/im.jpg" alt="picture"/>
		<span class="button blue square likes">9 Likes</span>
	      </li>
	      <li class="comment_data">
	           <ul class="post_info_options">
	   		<li class="commenter_name">Abc</li>
			<li class="comment"><p>hello how are you doing</p></li>
			<li class="time">
                            <span class="comment_time">12 June 2012<>
                           <span class="time_elapsed">7 hours ago</span>
              </li>
	     <li class="options">
                 <span><a href="#">Once More</a></span>
                 <span><a href="#">Comment</a></span>
                 <span><a href="#" class="comment_like">Like</a></span>
             </li>
						
	     <li>
										
	     </li>
	 </ul>
	</li>
	<li class="delete_comment"><img src="images/Cancel.png" alt="delete_post"/></li>
						
       </ul>
       <br/>

       	<ul class="comment_struct">
			
	      <li class="commenter_pic">
		<img src="images/im.jpg" alt="picture"/>
		<span class="button blue square likes">9 Likes</span>
	      </li>
	      <li class="comment_data">
	           <ul class="post_info_options">
	   		<li class="commenter_name">Abc</li>
			<li class="comment"><p>hello how are you doing</p></li>
			<li class="time">
                            <span class="comment_time">12 June 2012<>
                           <span class="time_elapsed">7 hours ago</span>
              </li>
	     <li class="options">
                 <span><a href="#">Once More</a></span>
                 <span><a href="#">Comment</a></span>
                 <span><a href="#" class="comment_like">Like</a></span>
             </li>
						
	     <li>
										
	     </li>
	 </ul>
	</li>
	<li class="delete_comment"><img src="images/Cancel.png" alt="delete_post"/></li>
						
       </ul>
       <br/>



       	<ul class="comment_struct">
			
	      <li class="commenter_pic">
		<img src="images/im.jpg" alt="picture"/>
		<span class="button blue square likes">9 Likes</span>
	      </li>
	      <li class="comment_data">
	           <ul class="post_info_options">
	   		<li class="commenter_name">Abc</li>
			<li class="comment"><p>hello how are you doing</p></li>
			<li class="time">
                            <span class="comment_time">12 June 2012<>
                           <span class="time_elapsed">7 hours ago</span>
              </li>
	     <li class="options">
                 <span><a href="#">Once More</a></span>
                 <span><a href="#">Comment</a></span>
                 <span><a href="#" class="comment_like">Like</a></span>
             </li>
						
	     <li>
										
	     </li>
	 </ul>
	</li>
	<li class="delete_comment"><img src="images/Cancel.png" alt="delete_post"/></li>
						
       </ul>
       <br/>
						
                                        
</div>


I have html structure as above .. so starting from $('.comments_container') how can i traverse to the last span in the DOM with class 'comment_time'. Help would be appreciated.

traversing using children() is possible. But i want to know is there any simpler way  