149 
rated plate (a. d.), by which the filaments of the olfactory 
nerve leave the skull. Again, a line drawn through the axis of 
the face, between the bones called ethmoid and vomer—the 
Beaver. d 
Lemur. 
Baboon. 
Fic. 29.—Longitudinal and vertical sections of the skulls of a Beaver (Castor 
Canadensis), 2 Lemur (L. Catta), and a Baboon (Cynocephalus Papio), ab, 
the basicranial axis; be. the occipital plane; ¢ 7, the tentorial plane; a@ d, the 
olfactory plane; fe, the basifacial axis; c b a, occipital angle; 7’ ia, tentorial 
angle; dab, olfactory angle; ef b, cranio-facial angle; gh, extreme length of the 
cavity which lodges the cerebral hemispheres or ‘ cerebral length.’ The length 
of the basicranial axis as to this length, or, in other words, the proportional length 
of the line g % to that of a b taken as 100, in the three skulls, is as follows:—Bea- 
ver 70 to 100; Lemur 119 to 100; Baboon 144 to 100. In anadult male Gorilla 
the cerebral length is as 170 to the basicranial axis taken as 100, in the Negro 
(fig. 30) as 236 to 100. In the Constantinople skull (fig. 30) as 266 to 100. 
The cranial difference between the highest Ape’s skull and the lowest Man’s is 
therefore very strikingly brought out by these measurements. 
In the diagram of the Baboon’s skull the dotted lines d'd?, &c. give the angles 
of the Lemur’s and Beaver’s skull, as laid down upon the basicranial axis of the 
Baboon. The line a d has the same length in each diagram, 
