14 EINAE LÖNNBERG, STUDIES ON RUMINANTS. 



breaking forcc at tlie base. For that purpose the core is strengthened in the plaiie 

 of attack in such a way that its transversal section is not round, but ovate with tlie 

 smaller ciid directed forward. In this \vay the increase in strength is eöected with 

 retrenchment of mateiial. The small longitudinal ridges on the inner side of the shea-tli 

 help to fästen it to the core and have, at the same time, a bracing eftcct. The rings 

 constitute a visefiil help against corrugatiou as well as torsion. 



Although 1 only know the, to the Saic/a related, Chiru from the literature tlie foUowing 

 note might be inserted as the horns of this animal exteriorly show sorae adaptations of 

 the kind about which it is here spöken. The long, nearly straight and sharply pointed 

 horns of this antelope {Pantliolops hodj/soni) are compressed from the sides and ringed 

 in front. Both these characteristics indicate a mechanical arrangement to strengthen the 

 horn in the sagittal plane resp. against breaking and corrugation of the sheath. From 

 the observations made by Przevalski it is known that the bucks of this species tight 

 desperately during the rutting season and often kill each other with these weapons. 



The horns of Antilope cervicapra resemble, to some extent, those of Saiga, but are, 

 thanks to their strong spiral rotation, more complicated. The horny sheath which gi^-es 

 the impression of being composed of a firmer material than that in the Saic/a-horns, is 

 provided with a great number of annular thickenings. These are, ho^vever, as a rule, 

 not complete. Having been developed on the originally anterior and median side they 

 leave, especially the first developed (resp. upper ones) an open space behind (resp. laterally). 

 In a låter period this open space is more and more narrowed so that the basal rings 

 in a fuUgrown, or at Icast almost fullgro\vn, horn^) meet posteriorly, although irregular 

 and less pronouiiced behind. In some horns the rings are partly somewhat displaced in 

 such a way that an almost complete spiral is formed. This is usually most conspicuous 

 on the middle of the horn. The length of the core is about 55 — 60 96 of that of the 

 sheath. The latter is thus strongly developed. The former is nearly as solidly built 

 as that of Sau/a, but is also similar to that of Strepsiceros. The basal half is nearly 

 compact although its centre is proximally occupied by a tissue resembling that which 

 has been described above from the Sai(/a-cove, viz. a dense bony tissue perforated by 

 line canals and longitudinal pores. The pores are somewhat larger than in Sair/a, but 

 the tissue cannot very well be detined as spongious. In addition to these pores are 

 seen some very few canals of greater dimensions for larger bloodvessels. Towards the 

 middle of the core these become more numerous and the aspect then agrees with that 

 offered by the core of the kudu. In the distal half the number of lai'ge canals for 

 ^■essels is still increased and the tissue occupying the interspaces becomes less dense, 

 and in the tip partly spongious. There is no sinus at the base, its place being occupied 

 by the dense but porous tissue mentioned above. The outer layer of perfectly compact 

 bone is at the base, where the risk of breakage is greatest, thicker anteriorly (7 mm.) 

 and posteriorly (6 mm.) than at the sides (3 mm.). This indicates that the horn is prin- 

 cipall}' adapted to endure a force working in the sagittal plane. But, on the other hand, 

 the transversal section of the base is round and has not been modified as i Saiqa. In 



V) The greatest horn at haud lueasures 47 cm. iu straight axial leugth. 



