KUNGL. SV. VET. AKADBMIENS HANDLINGAR. BAND 58. N:0 2. 4.3 



dimensions of the facial portion of the skull are compared. Thus the palatal length of 

 the young with milk-dentition is less than a third of the length of the whole skull, and only 

 38,3 % of the corresponding palatal measurement of the adult. In the skull with the first 

 molar developed the rostral portion has increased so much that the palatal length is 

 contained only 2 Vs times in the length of the skull, and if compared with the palatal length 

 of the adult the percentage is 55,5 %. In the semiadult skull with the second molar de- 

 veloped the palatal length is contained about 2 Va times in the length of the skull, and it 

 represents 73,7 % of the palatal length of the adult. The rostral portion of the skull thus 

 increases in length pari passu with the development of the dentition. From the begin- 

 ning the general shape of the skull of the young Baboon with milk-dentition is very similar 

 to that of f . i, an adult Cercocebus-skvll. It is first with the fuller development of the 

 permanent dentition that it becomes »dog-faced». 



This development of the dog-like shape of the skull appears to increase most ra- 

 pidly at the age when the second molar grows up. This can be found by comparing fig. 

 2 and fig. 3 of PL VII and by the following relative measurements. The length of the 

 face, measured from the mesial point of the superciUary ridge to the tip of the premaxil- 

 lary, is in the young Baboon with milk-dentition only 52 % of the total length of the 

 skull, and in the young Baboon with the first molar fully developed the relation is the 

 same, viz. up to that time the different portions of the skull have grown in practically 

 the same proportions. In the semiadult Baboon again with the second molar developed 

 the length of the face measured as above is not less than 59,6 % of the total length of 

 the skull, and in the adult it is 62 %, 



The final modelling of the male skuU follows first after the development of second 

 molar at the same time as the canines attain their full size, the third molars develop, 

 and the animal reaches maturity. With the development of the dentition the mus- 

 culature of the jaws increases very strongly which in a high degree influences the bones. 

 The zygomatic arches are widened and strengthened (cf. PI. VII, fig. 3 & 4), and at the 

 same time also the walls of the orbit etc. The interorbital wall grows to almost the double 

 thickness. The preorbital portion of the nasals increases with about 50 percent as com- 

 pared with the semiadult, and so on, which aU can be concluded from the recorded 

 measurements. 



The skull of the adult female (PI. VII, fig. 5) is in general shape rather similar to 

 that of the semiadult male (PI. VII, fig. 3) with the second molar developed, in spite of 

 the fact that the snout of the female is narrower and has no swollen lateral ridges etc. 

 as the male. This likeness is probably due to an analogous development of the muscu- 

 lature of the jaws in the female and the semiadult male. The female has no very large 

 canines, and those of the male in the stage mentioned have not yet developed to greater 

 size than those of the female. The armature of both is thus similar and much less power- 

 ful than that of the adult male. The zygomatic width is therefore almost alike, the same 

 is still more the case with the width across the middle of the orbit. The difference in 

 palatal length is only 3 mm. in favour of the semiadult male. The length of the face 

 from the mesial point of the supraorbital ridge to the tip of the premaxillary is only 

 about 4 mm. longer in the adult female than in the semiadult male. 



