Such are the elements from which it has been attempted to deduce some conclusions of general import in regard to the successive primitive races that have occupied Scotland prior to the era of authentic historic records. The data are much too few to justify the dogmatic assertion of any general inferences, or to admit of positive answers to the questions naturally suggested by the conclusions arrived at by Nillson and Eschricht in relation to the races of Scandinavia. They include, however, all the examples that could be obtained, and are in so far valuable as trustworthy examples of the cranial characteristics of Scottish races, that they have been selected from various localities, by different individuals, with no single purpose in view. It is difficult, however, even after obtaining the proper crania, to determine the most trustworthy elements of relative proportion. Dr. Walter Adam, who had the advantage of studying under both Dr. Barclay and Mr. Abernethy, carried out an extensive series of measurements of crania, chiefly from examples found in the catacombs of Paris, and preserved in the University Museum there. These I now possess, through the kindness of Dr. Adam, and he remarks in writing to me on the subject:--"So far as appeared, precision could only be obtained by referring every dimension to the compression of the zygoma; the measurement being seven-eighths of what I consider the normal transverse of at least the Caucasian cranium; that is, of half the length of the head--the long-admitted statuary scale." Owing to the imperfect state of the zygomata in the great majority of skulls from the tumuli, this measurement is unfortunately rarely attainable. Next in importance, however, is one of the additional ones in the table, marked as the inter-mastoid line, from the upper root of the zygomatic process. The relative proportions of this and of the parietal diameter, when compared with the longitudinal diameter, afford the most characteristic elements of comparison between the different types. Another interesting element of comparison appears to consist in the relative proportions of the parietal and vertical diameters. So far as appears from the table of measurements, the following laws would seem to be indicated:--In the primitive or elongated dolicho-kephalic type--for which the distinctive title of kumbe-kephalic is here suggested--the parietal diameter is remarkably small, being frequently exceeded by the vertical diameter; in the second or brachy-kephalic class, the parietal diameter is the greater of the two; in the Celtic crania they are nearly equal; and in the medieval or true dolicho-kephalic heads, the parietal diameter is again found decidedly in excess; while the preponderance or deficiency of the longitudinal in its relative proportion to the other diameters, furnishes the most characteristic features referred to in the classification of the kumbe-kephalic, brachy-kephalic, Celtic, and dolicho-kephalic types.