KUNGL. SV. VET. AKADBMIBNS HANDLINGAR. BAND 48. N:0 5. 163 



The length of the horns of my two Waterbucks is, measured along the anterior 

 curve, about 57 — 58 cm., and two other bucks shot for trophies by Mr. Sjogren 

 near the same place had exactly the same length of the horns so that this measure- 

 ment appears to be the »normal» at Guaso Nyiri below Chanler Falls, but the spread 

 of the horns varies considerably. It was in these four bucks about 22 Va, 27 V^. 29, 

 and 32 cm. 



The measurements of the typical skull of K. e. thikce is a little larger than the 

 Guaso Nyiri skulls the basal length being 349 mm. according to Matschie (1. c. p. 

 411), and the greatest breadth 162 mm. The distance between the posterior surface 

 of the occipital condyle and the anterior margin of the orbit is in Matschie's type 

 specimen 185 mm. »also nur 23 mm. langer als die grosste Breite des Schadels». 

 Matschie lays much stress upon the great breadth of the skull of K. e. thikce, and 

 he appears to regard this as a typical characteristic of that animal. If a comparison 

 is made between the basal length of the skull and its greatest breadth, the latter 

 measurement is found to be 46 % of the former according to Matschie's measure- 

 ments of K. e. thikce. In a similar way the corresponding percentages for the skulls 

 of my two Waterbucks from Guaso Nyiri prove to be resp. 46, and 47, and the 

 difference between the greatest breadth of the skull and the distance between the 

 occipital condyle and the front margin of the orbit is resp. 25 and 19 mm. But 

 this great relative breadth of the skull is nothing characteristic of the northern 

 Waterbucks of the ellipsiprymnus group alone. The measurements of a skull of a 

 Waterbuck from South Africa recorded above show that the breadth of the same is 

 46 °/o of the basal length there as well. These proportions are thus alike in southern 

 as well as in northern specimens. 



To judge from Matschie's measurements of the typical skull of K. e. thikce it 

 appears to be a little larger than my two skulls from Guaso Nyiri but the difference 

 is not great and might easily be individual. For the present no other cranial diffe- 

 rences of importance can be pointed out, and it is thus rather uncertain whether 

 the differences in colour and pattern justify the creation of a different subspecies 

 for the Waterbucks of the Guaso Nyiri district. Against Matschie's formal decla- 

 ration it is, however, difficult for the present to identify his very dark K. e. thikce 

 with my pale specimens from Guaso Nyiri, and although unwillingly I have felt 

 myself compelled to give them a separate name until the question can be fully solved 

 by more material. 



The paleness of the Waterbucks along Guaso Njnri appears to reach its extreme 

 in some individuals at and near the Lorian Swamp, where I heard that » white Wa- 

 terbucks* had been repeatedly observed. Such a one is reported in Proc. Zool. Soc. 

 London 1905 II p. 297, and in »The Field* the »white Waterbucks* from this loca- 

 lity have been mentioned more than once, and it has been stated that the eyes of 

 these white specimens are »of the normal colour, not pink».^ This makes this white 

 variation to something more than the common pathological pink-eyed albino which 

 now and then occurs among many different species of mammals. 



1 Conf. also the Extract in The Journal of the East Africa and Uganda Nat. Hist. Soc. Vol. II, N:o 3, p. 75. 



