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degree of bending of the cranial base, shifting of the anatomical 
points towards which the legs of the angle diverge). Hence in this 
communication a different method will be followed which will be 
presently explained *). 
This paper contains the first results of an investigation on the 
anatomy of the Primate skull, especially based on the study of the 
median plane. In order to prevent repetitions in subsequent commu¬ 
nications I shall begin with an enumeration of the materials used. 
In following papers reference may then be made to this enumeration. 
All skulls were cut in two along the median plane which was 
then drawn in natural size by means of the Martin pantograph, 
except the small skulls of Hapale, which were drawn at twice 
their natural size. The mediagrams of the foetal human skulls were 
made differently. All measures, ratio numbers, etc. which will be 
given now and later, have been derived from the mediagrams, unless 
the contrary is expressly stated. 
Human skulls. 
20 foetal skulls 
10 skulls from the first year 
t— 2 nd year 
4 th — 5 th 
5th _ 7th 
7 th — 8 th 
8th_ioth 
10 th —12 th 
10 dolichocephalic skulls (Frisians) Ind. ceph. average 75.7 
^ » „ (Papouas) „ „ „ 67.5 
10 » „ (Negroes) „ „ „ 71.2 
10 brachycephalic skulls (Zeelandians) „ „ „ 84.8 
^ » „ (Javanese) „ „ „ 82.7 
Besides median sections were made through JO other dolichocephalic 
s nils with an average index of 74,8, the origin of which was not 
accurately known, however. 
t work on comparative craniometry of the Primates (that of Aeby) 
other works also in this respect, that in it ratio numbers are used 
possible and angular values as little as possible. C. Aeby. Die 
der Menschen und der Affen. Leipzig 1867, 
25 * 
