У меня есть этот код и каждые 3, мне нужно обернуть с DIV

(Оригинал)

<div id="entries"> 
<a class="thumbnaila"><img class="thumbnail" alt="" src="blabla"/></a>
<a class="thumbnaila"><img class="thumbnail" alt="" src="blabla"/></a>
<a class="thumbnaila"><img class="thumbnail" alt="" src="blabla"/></a>
<a class="thumbnaila"><img class="thumbnail" alt="" src="blabla"/></a>
<a class="thumbnaila"><img class="thumbnail" alt="" src="blabla"/></a>
<a class="thumbnaila"><img class="thumbnail" alt="" src="blabla"/></a>
<a class="thumbnaila"><img class="thumbnail" alt="" src="blabla"/></a>
</div>

(должен стать)

<div id="entries"> 
<div>
<a class="thumbnaila"><img class="thumbnail" alt="" src="blabla"/></a>
<a class="thumbnaila"><img class="thumbnail" alt="" src="blabla"/></a>
<a class="thumbnaila"><img class="thumbnail" alt="" src="blabla"/></a>
</div>
<div>
<a class="thumbnaila"><img class="thumbnail" alt="" src="blabla"/></a>
<a class="thumbnaila"><img class="thumbnail" alt="" src="blabla"/></a>
<a class="thumbnaila"><img class="thumbnail" alt="" src="blabla"/></a>
</div>
<div>
<a class="thumbnaila"><img class="thumbnail" alt="" src="blabla"/></a>
</div>
</div>