KONGL. SV. VKT. AKADEMIENS IIANDLINGAK. BAND. 35. NIO 3. 27 



be suspected althougli not so plaiiily seen. In cevtaiii li^dits they becouie howcner rather 

 conspicuous on a longitudinal section of thc core. The tip is quite solid. The honiy 

 sheath is not \ery thick except at the base, where tlie portion covering the sinuous eore 

 partly exceeds 1*2 cm. in thickness. At tlie curve the thickness of the sheath is ou the 

 concave side 4 mn»., but on the con\ex 7 mm. Except at the base where the siirface 

 is ragged the horny sheath is sniooth. There are consequently no special arrangements 

 for the strengthening of the sheath wliich compared with that of the caama seems weak. 

 Tlie horn is at the curve considerably compressed from the sides. The area of section 

 of this ])art is ovate with the broader end at the concaAe side of the curve. This agrees 

 thus Avith the condition found in the corresponding part of the horn of the caama. There 

 is also a considerable analogy of shape betAveen the horn of the gnu and the draghook 

 of a railway-car made in accordance witli mechanical principles. Both are designed to 

 endure without risk of breaking the greatest possilile pulling force with the least possible 

 expenditure of material resources. Thc proximal part of the horn is, on the other hand, 

 affected in a different way. It is, namely, mostly subjected to a breaking force and torsion 

 working in a direction nearly forming a right angle to that of the pulling force working 

 on thc hook. This depends on the habit of the gnu to strike sideways with its horns, 

 as we are informed in the literature. To withstand this violence the proximal part of 

 the horn must accordingly be strengthencd in a different pla-ne than the hook. That part 

 of the horn which lies between the hook and the base is also vertically flattened, or in 

 a direction opposite to that in A\hich the hook is com|)ressed. The area of section is also 

 in this case OAate and its broad end is on the posterior side. There is thus iu this casc 

 as well, a mechanical adaption. The attachment to the skull is exceedingly strong by 

 means of the broadlv expanded l)ase the longest diameter of which is extended in the 

 sagittal plane ;ind in thc specimen on hand ineasures 17 cm. To prevent the sheath 

 frcnn gliding on the core Avhen pulled, the thickened l:)ase of the former covers and 

 sui'rounds the protruding sinuous base of the latter like a cap. Th<' sheath can therefore 

 be said to be quite clenched to the skull especially by completely cajiping the great 

 occi])ital knob of the basal core. Gliding is thus made impossible and a force working 

 on the horn must affect horny sheath and core alike. The hoi-n of the gnu is evideritly 

 a strongly and according to mechanical principles built orga.n. The great development 

 and conipactness of the bon^- core compared with the rather thin horny sheath seems to 

 represent a rather primitive stage of de\'eIopraent, but with regard to the specialised 

 shai^e and the extensive basal sinus etc. the horns of the gnu seera fairly advanced. 

 The hoi-ns of the brindled gnu {CimnoeIia'te.s taurinus (BuRCri.)) are not so specialised as 

 those of the whitetailed one. The bases are in the former not so expanded. >>The Ijasal 

 two-thirds of the horn points directly outwards» and is vertically flattened. »The ends 

 are curved uj)wards, forwards and inwards».') With such a sliape of the horns they must 

 be used obliquely sideways and in such a case the depression of the proximal portion 

 might have a strengthening effect in the |)lane in which thc breaking power is working.'") 



^) Book of iintelopes II )i. 96. 



-) Vrolik 1. c. biis also a tigure representiug a longitudinal section of a horn of C. ;/nu: about this raay 

 be said the same as above with regard to his tigure of a horn of Buhalis caama. 



