ters in the Alpine highlands, running up to the north; the other, in Auvergne, extends away toward the Spanish frontier. At the present time let us note that this intrusive strip of long heads cutting the Alpine belt in two follows the exact course of the canal which has long united the head waters of the Loire with the Rhone. It is an old channel of communication between Marseilles and Orleans. Foreigners, immigrating along this highway, are the cause of the phenomenon beyond question.
The long-headed populations therefore seem to follow the open country and the river valleys. The Alpine broad-headed type, on the other hand, is always and everywhere aggregated in the areas of isolation. Its relative purity, moreover, varies in proportion to the degree of such isolation enjoyed or suffered. In Savoy and Auvergne it is quite unmixed; in Brittany only a few vestiges of it remain. And yet these few remnants are strictly confined within the inhospitable granitic areas, so that the boundaries of the two correspond very closely. The spoken Celtic tongue has also lingered here in Brittany for peculiar reasons, which we shall soon discuss. The main one is the isolation of the district, which has sheltered the Alpine race in the same way. For it is now beyond question that the Breton, the Auvergnat, and the Savoyard are all descendants of the same stock. In nearly every case the Alpine race is found distributed, as Dr. Collignon says, "by a mechanism, so to speak, necessary, and which by the fatal law of the orographic condition of the soil ought to be as it is." In the unattractive or inaccessible areas the broad-headedness centers almost exclusively; in the open, fertile plains the cephalic index falls as regularly as the elevation. So closely is this law followed that Dr. Collignon affirrms of the central plateau that wherever one meets an important river easily ascended, the cephalic index becomes lower and brachycephaly diminishes.
The two-hundred-metre line of elevation above the sea seems most nearly to correspond to the division line between types. This contour on our geographical map is the boundary between the white and first shaded areas. Compare this map with that of the cephalic index, following round the edge of the Paris basin, and note the similarity in this respect. There is but one break in the correspondence along the eastern side. This exception it is which really proves the law. It is so typical that it will repay us to stop a moment and examine. We have to do, just south of Paris, with that long tongue of dark tint, that is of relative broad-headedness, which reaches away over toward Brittany. It nearly cuts the main axis of Teutonic racial traits (light tinted) in two. This is the department of Loiret, whose capital is Orleans. It is divided from its Alpine base of supplies by the long-
