length and multiply the result by 100 we get what is known as the cephalic index of the skull.  Thus if a skull has a length of 180 millimetres and a breadth of 135, its cephalic index is 135/180 X 100, i.e. 75.  It is clear that in a roundish type of head the breadth will be greater in proportion to the length than in a narrow elliptical type.  Thus in a broad head the cephalic index is high, while in a narrow head it is low.  The former is called brachycephalic (short-headed), and the latter dolichocephalic (long-headed).

This index is now accepted by most anthropologists as a useful criterion of race, though, of course, there are other characteristics which must often be taken into account, such as the height and breadth of the face, the cubic capacity of the skull and its general contour.  At any rate, if we can show that the skulls of the megalithic tombs conform to a single type in respect of their index we shall have a presumption, though not a certainty, that they belong to a single race.

For Africa the evidence consists in a group of twenty skulls from dolmen-tombs giving cephalic indices which range from 70.5 to 84.4.  The average index is 75.27, and the majority of the indices lay within a few units of that number.  Ten skulls from Halsaflieni in Malta have cephalic indices running from 66 to 75.1, the average being 71.84.  Of a series of 44 skulls from the rock-tombs of the Petit Morin in France, 12 had an index of over 80, 22 were between 75 and 80, and 10 were below 75.  But in the dolmens of Lozere distinctly broad skulls were frequent.  A series of British neolithic skulls, mostly from barrows, ran from 67 to 77.

The builders of the megalithic monuments thus belonged in the main to a fairly dolichocephalic race or races, for the large majority of the skulls measured are of a long-headed type.  There are, however, in various localities, especially in France, occasional anomalous types of skull which are distinctly brachycephalic, and show that contamination of some kind was taking or had taken place.

Of the state of civilization to which the builders of the megalithic monuments had attained, and of the social condition in which they lived, there is something to be gathered.  It is clear in the first place from the evidence of the Maltese buildings that they were a pastoral people who domesticated the ox, the sheep, the pig, and the goat, upon whose flesh they partly lived.  Shellfish also formed a part of their diet, and the shells when emptied of their contents were occasionally pierced to be used as pendants or to form necklaces or bracelets.

Whether these people were agricultural is a question more difficult to answer.  It is true that flat stones have been found, on which some kind of cereal was ground up with the aid of round pebbles, but the grain for which these primitive mills were used may have been wild and not cultivated.  No grain of any kind has been found in the Maltese settlements.