$(document).ready(function() {
    $('#portfolio div').hide();
    $('#portfolio div:first').show();
    $('.portNav .prev').click(function(){
        current = $('#portfolio div:visible').get();
        $(current).hide();
        if ($(current).prev().length == 0) {
            $('#portfolio div:last').show();
        } else {
            $(current).prev().show();
        };
        return false;
    });
    $('.portNav .next').click(function(){
        current = $('#portfolio div:visible').get();
        $(current).hide();
        if ($(current).next().length == 0) {
            $('#portfolio div:first').show();
        } else {
            $(current).next().show();
        };
        return false;
    });
});