334 
A Study of the Negro Skull 
may safely look upon the Gaboon and Congo as forming a fairly representative 
group*. 
(ii) This group differs sensibly from the Kaffir-Zulu group of Shrubsall, but 
negro crania from the north coast (our Northern negroes) seem to approach these 
southern negroes more closely than they do the Congo-Gaboon group. 
(iii) If we wish to determine characteristic negro features, but few absolute 
measurements are of any service. Thus the usual tape arcs, vertical, sagittal and 
horizontal, are of small differential value. There are, however, some exceptions to 
this rule. 
(a) The Negro skull is higher than the European, when we take the basio- 
bregmatic height. This excess, however, is not due to the development of the 
upper part of the cranium, there is sensible equality of the auricular heights. 
The increased height lies between the auricular passages and the basion. It is in 
fact due to the more massive character of the base of the negro skull. A good 
measure of this result is found in the index 100 OHjH, which is about 85 for 
Negroes and 87 — 88 for Europeans. 
(6) Notwithstanding that little of an orderly evolutionary scale can be made 
out from absolute measurements — diameters or arcs — the available data show 
that both for the Gaboon-Congo and the Northern Negro groups there is a great 
deficiency of cranial capacity — a difference of 100 to 150 cm. 3 — between Negro and 
modern European races. 
(c) The nature of this difference in cranial capacity appears to be principally 
occipital in origin. There is some difference in the average of tape measure- 
ments from nasion to bregma between English and Negro f, but the chief difference 
lies in the section from lambda to opisthion. If we measure the occipital pro- 
minence by the occipital index, we find the English cranium stands at 58 to 
59 and the Negro at 68 to 69, the flatter the cranium from opisthion to lambda 
the higher is this index. There is, I think, no doubt that relatively to the Negro 
the occipital portion of the skull in the European is greatly developed j. 
(iv) Certain indices — as distinguished from absolute measurements — seem to 
be of special value in differentiating European and Negro crania. 
(a) In the first place the ordinary cephalic indices (100 BjL and 100 HjL) 
are of small service, but a new index 100 (B — H)/L, which I have called the 
acroplatic index, is not only positive and fairly high for Europeans but is insensible 
or actually negative for Negroes. In this they agree with the primitive and 
* At the same time the mesodacryal and simotic indices show that the two series are by no means 
wholly alike. 
t To some extent indicated in the relative frequency of "markedly retreating foreheads " (see p. 331 
above) notwithstanding equality of auricular height. 
% This has been already indicated in the previous paper on cranial contours (Biometrika, Vol. vin. 
pp. 135, 136) and may be illustrated graphically by superposing Fig. XV in tissue on Fig. XXVII. 
