Add somethign before and after every group of 4 posts...

gistfile1.aw

<?php $tombstones = new WP_Query('category_name=tombstones&posts_per_page=-1'); ?>
<?php $counter = 0; ?>
<?php echo '<div class="slide"><h1>Beginning</h1>'; ?>
 <?php  if( $tombstones->have_posts() ) : while ( $tombstones->have_posts() ) : ?>
  <?php $tombstones->the_post(); $counter++; ?>

  <?php if ($counter % 4 == 0) echo '<h1>Ending</h1></div><div class="slide"><h1>Beginning</h1>'; ?>
  <?php the_content(); ?>
									
 <?php endwhile; endif;?>
<?php echo '<h1>Ending</h1></div>'; ?>
<?php wp_reset_postdata(); ?>