Perhaps he is armed with a club, and may take amiss the use of an instrument that has to be poked into his ears, or what not.

So, for one reason or another, we have often to put up with that very unsatisfactory single-figure description of the head-form which is known as the cranial index.

You take the greatest length and greatest breadth of the skull, and write down the result obtained by dividing the former into the latter when multiplied by 100.

Medium-headed people have an index of anything between 75 and 80.

Below that figure men rank as long-headed, above it as round-headed.
This test, however, as I have hinted, will not by itself carry us far.
On the other hand, I believe that a good judge of head-form in all its aspects taken together will generally be able to make a pretty shrewd guess as to the people amongst whom the owner of a given skull is to be placed.
Unfortunately, to say people is not to say race.