ON THE BRAINS OF TWO IDIOTS OF EUROPEAN DESCENT. 
505 
inches. 
Extreme width at the parietal eminences 5*5 
Extreme depth of the cranium, from beneath the occiput 
to the vertex 5 "5 
From one external auditory meatus to the other . . . 12*5 
From the root of the nose to the occipital protuberance 12 
Circumference close above the ears ....... 21 
The proportions between the length and breadth of the cranium, which are as 100 to 
76, show that it is not nearly so dolichocephalic as the Negro skull. In its thickness, 
however, it resembles the latter. The thinnest part on the median section is over the 
vertex, and measures 3 of an inch ; passing backwards, the thickness of the parietal 
bone increases to *35 of an inch, whilst the occipital protuberance exceeds • 5 of an inch; 
passing forwards, the average thickness of the frontal bone is about ’35 of an inch, 
increasing at the forehead itself to ‘5 of an inch. The diploe is scarcely distinguishable, 
owing to the closeness of the bony texture. There is no appearance of frontal sinuses. 
The foramen magnum measures 1*4 inch in its antero-posterior diameter and T3 inch 
transversely; its anterior border corresponds with a line passing across *375 of an inch 
behind the internal auditory meatuses. All the sutures at the top of the skull are 
closed; the line of the fronto-parietal is quite obliterated, that of the sagittal suture 
nearly so, whilst the lambdoidal suture can still be traced. The squamous part of the 
left temporal bone is also absolutely joined to the frontal and parietal. The petrosal 
and other ridges in the base of the cranium are prominently marked ; the crista galli is 
large, and the sella turcica deep. The internal surface of the cranium is more strongly 
marked than usual by the convolutions, especially in the orbital, frontal, temporal, and 
occipital regions, but much less distinctly so along the vertex. The auditory meatuses 
and optic foramina are small ; the cribriform lamellae are of moderate extent ; the other 
foramina are of average size. On the outer surface of the cranium the zygomatic arches, 
though of well-marked curvature, are slender; the mastoid processes are very small, 
and the styloid processes also slender. 
The right half of the cranium, as defined by the falx, which, together with the tento- 
rium, was left undisturbed, holds nearly exactly 17‘5 oz. avoirdupois of water; so that 
the total capacity of the entire cranial cavity is about 35 oz. of water, which are equal 
to 6064 cubic inches. Thus the actual capacity of the cranial cavity proved to be less 
than its external dimensions would have led one to anticipate. The capacity of the 
largest skull measured by Morton* was 114 cubic inches. The largest examined by 
Wagner f was 115 cubic inches ; the smallest, that of an adult female, 55*3 inches. As 
measured in ounces of water, the capacity of the male Hottentot’s skull has been given 
as high as 75 cubic inches; whilst that of the Negro’s ranges from 69*3 to 60-5 cubic 
inches, that of the Malay’s skull from 62*2 to 57T cubic inches, and that of the Hindoo’s 
* Crania Americana. Philadelphia, 1839. 
t Yorstudien zu einer Morph, und Phys. des menschlichen Gehims. Leipzig, 1860. 
