CRANIOLOGY. 173 
superior and inferior maxillee become absorbed owing to the loss of the teeth. This gives 
rise to a flattening of the vault of the hard palate and an alteration in the form of the 
lower jaw, whereby the mandibular angle becomes more obtuse. 
CRANIOLOGY. 
The various groups of mankind display in their physical attributes certain features which are 
more or less characteristic of the stock to which they belong. Craniology deals with these 
differences so far as they affect the skull. The method whereby these differences are recorded 
involves the accurate measurement of the skull in most of its details. Such procedure is included 
under the term craiiometry. Here only the outlines of the subject are briefly referred to ; 
for such as desire fuller information on the subject, the works of Broca, Topinard, Flower, and 
Turner may be consulted. 
The races of man display great variations in regard to the size of the skull. Apart altogether 
from individual differences and the proportion of head-size to body-height, it may be generally 
assumed that the size of the skull in the more highly civilised races is much in excess of that 
displayed in lower types. The size of the head is intimately correlated with the develop- 
ment of the brain. By measuring the capacity of that part of the skull occupied by the 
encephalon, we are enabled to form some estimate of the size of the brain. The cranial capacity 
is determined by filling the cranial cavity with some suitable material and then taking the 
cubage of its contents. Various methods are employed, each of which has its advantage. The use 
of fluids, which of course would be the most accurate, is rendered impracticable, without special 
precautions, owing to the fact that the macerated skull is pierced by so many foramina. As a 
matter of practice, it is found that leaden shot, glass beads, or seeds of various sorts are the most 
serviceable. The results obtained display a considerable range of variation. For purposes of 
classification and comparison, skulls are grouped according to their cranial capacity into the 
following varieties :— 
Microcephalic skulls are those with a capacity below 1350 cc., and include such well-known 
races as Andamanese, Veddahs, Australians, Bushmen, Tasmanians, ete. 
Mesocephalic skulls range from 1350 c.c. to 1450 cc., and embrace examples of the following 
varieties : American Indians, Chinese, some African Negroes. 
Megacephalic skulls are those with a capacity over 1450 c.c., and are most commonly met 
with in the more highly civilised races: Mixed Europeans, Japanese, Eskimo, ete. 
Apart from its size, the form of the cranium has been regarded as an important factor in the 
classification of skulls; though whether these differences in shape have not been unduly em- 
phasised in the past is open to question. 
The relation of the breadth to the length of the skull is expressed by means of the cephalic 
index which records the proportion of the maximum breadth to the maximum length of the 
skull, assuming the latter equal 100, or— 
Max. length x 100 
-_—- — Cephalic index. 
Max. breadth Cephalic index 
The results are classified into three groups :— 
1. Dolichocephalic, with an index below 75: Australians, Kaftirs, Zulus, Eskimo, Fijians. 
2. Mesaticephalic, ranging from 75 to 80: Europeans (mixed), Chinese, Polynesians (mixed). 
3. Brachycephalic, with an index over 80: Malays, Burmese, American Indians, Anda- 
manese. 
In order to provide for uniformity in the results of different observers, some system is neces- 
sary by which the various points from which the measurements are taken must correspond. 
Whilst there is much difference in the value of the measurements insisted on by individual 
anatomists, all agree in endeavouring to select such points on the skull as may be readily deter- 
mined, and which have a fairly fixed anatomical position. The more important of these “ fixed 
points” are included in the subjoined table :— 
Nasion.—The middle of the naso-frontal suture. 
Glabella.—A point midway between the two superciliary ridges. 
Ophryon.—The central point of the narrowest transverse diameter of the forehead, measured 
from one temporal line to the other. 
Inion.—The external occipital protuberance. 
Maximum Occipital Point.—The point on the occipital squama in the sagittal plane most 
distant from the glabella. 
Opisthion.—The middle of the posterior margin of the foramen magnum. 
Basion.—The middle of the anterior margin of the foramen magnum. 
Bregma.—The point of junction of the coronal and sagittal sutures. 
Alveolar Point.—The centre of the anterior margin of the upper alveolar margin. 
Subnasal Point.—The middle of the inferior border of the anterior nasal aperture at the 
centre of the nasal spine. 
Vertex—The summit of the cranial vault. 
