88 



EINAR LONNBBRG, MAMMALS COLLECTED IN OEKTEAL AFRICA. 



depressed, and therefore with a greater transverse diameter amounting to 21 mm. bas- 

 ally at its maximum. 



Total length of skull 



Basal » " » 



Zygomatic breadth of skull 



Breadth of brain-case 



Distance from orbit to tip of premaxillary . . 



Length of nasals 



Least interorbital width 



Greatest breadth of nasals (at lacrymal suture) 

 Width of nasals at nasi-premaxillary Buture . 



Length of upper molar series (worn !) 



Breadth of to' 



9 

 Beni ad. 



197 mm. 



174,5 » 



86 » 



61 » 



107 » 



86 . 



43.3 » 

 32,8 » 



18.4 » 

 50 » 

 12,7 » 



Kabwe ad. 



185,3 mm. 



166 » 



85 » 



56.3 » 

 96,5 » 

 71,8 » 

 45 » 

 36 » 

 21 y> 

 47,5 » 



13.4 » 



Kabwe ad. 

 (melanistic) 



185 mm. 



164 » 



86.5 » 

 60 » 

 96 » 

 73 » 



46.6 » 



36.4 » 



24.5 » 

 54,5 » 

 14,5 » 



These measurements prove very plainly that G. weynsi from Beni has a considerably 

 longer skull (PI. X, fig. 1) with a more elongate rostrum than the Rutshuru race (fig. 2), 

 while the latter is not only comparatively, but even absolutely broader in the nasal region. 

 The nasals do not project mesially so far backwards in the Duikers from Kabwe as in 

 that from Beni, nor are they so strongly produced forwards in their anterior end, but 

 everywhere broader. These features prove that the Duikers from Kabwe are not simply 

 smaller specimens of the same kind as that from Beni. Othermse both skulls, of course, 

 have a general resemblance. Characteristic to both is that the nasals are comparatively 

 flat above, especially in the specimens from Kabwe, but that the central portion of the 

 frontals, inside foramina swpraorbitalia is rather strongly raised to form a pronounced 

 convexity which in the specimen from Beni forms an almost roof-like ridge (PL X, fig. 

 1 & 2). The upper molar series are in both comparatively short, but the true molars 

 broad. 



On the lower jaw the angular flanges or lobes are very sharply set off (almost in 

 a right angle) from, and extend about a centimeter below the lower contour line of ramus 

 horizontalis (PI. X). This great expansion of the angular portion of the lower jaw indi- 

 cates that the diet of the animal requires a powerful development of the musculature of 

 the jaws especially m. masseter and m. pterygoideus inter nus. The strongly worn condi- 

 tion of the molars, and the fact that the inner sides of the upper, and the outer sides of 

 the lower molars are very much more worn down than the opposite sides prove that 

 the food-material has needed an intense grinding activity before it became useful for di- 

 gestion. Unfortunately nothing is known about the biology of these animals, but of all 

 species of Cephalophus represented in this collection, G. weynsi, with its subspecies, ap- 

 pears to be the most speciaUzed in this respect, and this as well as other structural fea- 

 tures prove that the different species of this genus, although inhabiting the same districts 

 must differ in a considerable degree with regard to their habits, diet etc. 



