KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 



35. n:o 3. 21 



pressed (anterior) side. But also on the posterioi* stretched side the rings may be useful 

 and add to the resistance. In the proximal third the core plays a more iuiportant part 

 and its compacta is thei-efore strongly developed. The trajectorios of stretching inay also 

 be useful, although they are only weakly represented. The widening of the base at the 

 insertion has also a strengthening effect on this part, which, as constituting the end of 

 the lever, is subjected to the greatest force. 



The horns of Hippotragus niger and H. equinus have essentially the same shape 

 and are also strongly compressed from the sides to obtain the greatest poAver of resistance 

 in the sagittal plane. 



In a specimen of H. niger the basal diameter of the core is, in the sagittal plane, 

 75 aiid in the transversal one 52 mm. A quotation from Selous (1. c. p. 757) gives an 

 idea of how well these animals know how to use their horns in case of beinff attacked. 



o 



»The Sable Antelope is often very savage when wouuded, and like the Roan Antelope 

 {H. leuarphoeus) and gemsbuck {Oryx gazella) will commit terrible havoc amongst a pack 

 of dögs; indeed I have known one to kill three -with three consecutive sweeps of its long 

 scimitar-sliaped horns.» 



Of Oryx gazella I have made a longitudinal section through the core, which reveals 

 the peculiar structure of the same. It can be compared to a long — in this case 66 cm. — 

 tapering tubc, the walls of which consist of compact bony tissue. This wall also tapers 

 in a distal direction. At the tip it is only one mm. in section or hardly so much, but 

 becomes gradually thicker proximally. Twcnty cm. from the tip the wall of the great 

 tube is (2 V- — )3 mm. in thickness anteriorly and 2 uim. posteriorly. This entire distal 

 stretch is almost completely hollow. The only exception to this being some very delicate 

 osseous threads or small groups of threads, thin enoiigh to be compared to parts of a 

 spiderweb, which are extended here and there. Next section of the core, also about 

 20 cm. in length, is tilled by a loose spongiosn, constituted by a network of fine threads 

 forming large meshes. In tlie third ;ind last section the compact wall of the core is 

 increased on the anterior side from 4 — 5 mm. to 8 — 10 nmi. in thickness, basally and 

 on the posterior side from 3 to 6 mm. resp. The interiör of this part is made up of 

 large tubelike canals for bloodvessels running longitndinally. The interspaces between 

 these tubes are tilled up by a coarse irregular spongiosa. Some of the canals go so peri- 

 pherically as to enter the outer compacta. In the base of tlie core is a large undivided 

 sinus liordered by compact walls. The thickness of these walls is anteriorly about 8 mm., 

 posteriorly about 6 mm. and laterally 12 mm. Through this the base of the core becomes 

 more resistant against violence from the side than in the sagittal plane. The base of the 

 core is widened, and this gives increased strength to the place where the greatest risk 

 of breakage is. At the same time the attachment to the skull becomes finner. But it is 

 to be obscrved, that the area of section is enlarged more in the transversal than in the 

 sagittal plane, Avhich consequently gives increased strength against attacks in the trontal 

 or transversal plane. The horny sheath which is ringed basally is also more like a tube 

 in this than in other antelopes. It is namely hollow through fully 85 % or more of its 

 whole length. The basal diameter of the horn seems to be only 6 % more or less of 

 its length. 



