20 EINAR LÖNNBERG, STUDIES ON RUMINANTS. 



basal part of the core is almost compact, and in its middle region the trajectories of 

 pressure are developed. The spiral twisting of the horn has a strengthening effect in case 

 of torsion, and also against breaking from all sides. The attachraent to the skull is made 

 firmer by considerably widening the core at the base, especially as it seems in a forward 

 direction. The transversal diameter of the base of the core is also shorter than that in 

 the sagittal plane (»Verlängerung des Querschnittes»). The origin of the sinus may stånd 

 in connection with the widening of the base of the core, which means a tendency to 

 arrange the resistant elements peripherically, as far as possible from the neutral axis. 



Of the Hijypotragine section or subfamily of antelopes I have had opportunity to 

 investigate the structui'e of the horns of Hippotragus leucophoeus and a South African Oryx. 

 The horny sheath of the former is very thick and strong in this animal, especially in the 

 distal part. It is thicker on the convex anterior side and surrounded by densely set 

 annular thickenings, which are almost transversally arranged and best developed on the 

 anterior side. The core extends through nearly 60 % of the total length of the horn, 

 which along the curve measures 57 cm. At the middle of the core the thickness of the 

 sheath anteriorly (11 mm.) equals about one fourth of the entire thickness of the horn 

 in the sagittal plane, basally it is about one sixth of the same dimension. In none of the 

 horns, hitherto described, the thickness of the sheath has been comparatively as great as 

 in Hipi^otragus. The core is, as in Antidorcas, provided with a basal sinus which of course 

 is surrounded by a strong wall of compact bony tissue, thickest in fi'ont and behind, 

 that is in the sagittal plane. For the purpose of making the attachment of the core 

 to the skull more effective the basal part including this sinus is considerably widened 

 proximally (a peripheric arrangement of the resistant elements). The bony walls are also 

 braced by strong trabeculaj, partly in the sagittal plane. Above the roof, of the sinus 

 is a portion of comparatively more weakly built spongiosa than elsewhere. But the whole 

 of the central region of the core is occupied by a rather coarse spongiosa which seems 

 irregular; I think, however, that in some places faint traces of trabeculaj may be discerned 

 extending from the concave posterior towards the anterior convex side of the core. It 

 seems thus as if only one system of trajectories was developed, but that is not by far 

 so conspicuous as in the cores of many other animals. The central spongiosa is traversed 

 by large canals for bloodvessels chiefly in the posterior half of the core. The meshes 

 of the peripherical spongiosa are, especially on the anterior side, longitudinally stretched. 

 The outer zone of compact tissue of the core is well developed över the entire length 

 of the organ. At the base it attains a thickness of a fourth or a fifth of the diameter 

 of the core anteriorly and posteriorly; on the sides it is thinner and becomes also thinner 

 in a distal direction, as usual, because the core is there sufficiently protected by the sheath. 

 The horns of Hippotragus are formidable weapons and adapted to use in the sagittal 

 plane giving blows or tearing up the adversary from below upwards. For that purpose 

 the material of resistance is chiefly arranged anteriorly and posteriorly, as has been described. 

 For the same reason the horns are strongly compressed from the sides the whole way 

 from the base to the tip, which increases the strength in the sagittal plane with retrench- 

 ment of material. The main strength of the distal two thirds lies in the horny sheath, 

 which is vei'y thick and braced by the rings to withstand torsion and corrugation of the 



