18 ARKIV rÖR ZOOLOGI. BAND 7. NIO 6. 



such places as ought to be iiihabited by the narrow-headed 

 boars for instance Inhambane in Portug. E. Africa, N. E. 

 Rhodesia, and Nyasaland have a comparatively broad parietal 

 region measuring resp. 33, 29, and 33 mm. or resp. 9, i, 8,4, 

 and 9,1^0 of the upper mesial length. The parietal dimen- 

 sions of the females are thus very similar as well in the dis- 

 trict of the broad-headed as in that of the narrow-headed 

 boars, if the old very broad-headed female from Natal is 

 excepted. This appears at the first look to be a puzzle which 

 is not easily explained. It might, however, be possible that 

 the females in both cases represent on earlier sta ge of deve- 

 lopment and that the males in the two districts have for 

 some reason been subjected to a diverging development. 

 That is, both races (if they are different) should originally 

 have had a parietal area of the intermediate size, thus about 

 9 7o of the upper mesial length. In the narrow-headed race 

 the females retained this relative dimension while the males 

 became comparatively more narrow-headed. In the broad- 

 headed race again the males and the old females developed 

 a broader parietal region amounting to more than 12% of 

 the upper mesial length of the skull. 



This hypothese is perhaps not quite satisfactory but 

 with the present material none better can be offered as ex- 

 planation of the existing differences between the shape of 

 the skulls of the boars which is so great and striking as to 

 hardly admit a lumping together of the two types, especially 

 if it is considered that this dimension is a rather constant 

 one within a race, as the tables of measurements pro ve in 

 more than one instance. 



A fact is that among the Bush Pigs of the Fotamochceriis 

 choeropotamus group specimens with a very broad parietal 

 area measuring 42 — 47 mm. and corresponding to 12,4 — 12,9 7o 

 of the upper mesial length of the skull are found in the Cape 

 Colony and Natal, while northward from these countries in 

 Portuguese East Africa, Mashonaland, N. E. Rhodesia etc. the 

 corresponding measurements in males are 24 — 26 mm. and 

 the percentages 6,2 — 6,9%. If w^e go still further north and 

 enter German East Africa the Bush Pigs in the southern 

 parts of this country will be found to possess a rather narrow 

 parietal area as the following notes from specimens in the 

 Berlin Museum appear to indicate. 



