poch the skull as assigned to, an
      ordered factor with levels <code>c4000BC</code> <code>c3300BC</code>, <code>c1850BC</code>,
      <code>c200BC</code>, and <code>cAD150</code>, where the years are only given approximately, of course.</p></dd>

  <dt><code>mb</code></dt>
<dd><p>maximal breadth of the skull.</p></dd>

  <dt><code>bh</code></dt>
<dd><p>basibregmatic height of the skull.</p></dd>

  <dt><code>bl</code></dt>
<dd><p>basialiveolar length of the skull.</p></dd>

  <dt><code>nh</code></dt>
<d