28 EINAR LÖNNBERG, STUJJIES ON RUMINANTS. 



As a representative of Rripricajrmue it is well tu considcr liiijjrieajyra as tlie iirst t}'pe. 

 A longitudiiial section throngli a. horn of this iiinuuil, uieasuriiig 17 ciu. from the laase 

 to the distal surface of the apieal cur\'e reveals the following conditions. The core attaiiis 

 a length of (98 mm.) nearly 10 cm. Its basal fifth is occupied hj an undivided sinus, 

 a prolongation of the frontal siniis. The walls snrronnding this basal sinus consist of 

 compact bony tissue. This continiies distally on the core forming its outer zone. This 

 layer is thicker on the |jOsterior than on the anteriov side. The thickness of the latter 

 Ijeing about 3 mm. and that of the former between 4 and 5 mm. in section in the 

 proximal half. Distally the compacta becomes tliirmer and more iri'egular. The tip of 

 the core is obliquely pointed so that it extends further posteriorly than anteriorly. The 

 interiör of the bony core consists of a ra.ther coarse spongiosa, in which, ho^ve^■er, the 

 trajectories according to Culmann's law are very ))ea,utifLdly developed. Both systems 

 of curves are almost evenly developed, afthough some trajectories are stronger than 

 others (conf. the tig. 8 Pl. I). They meet centrally in the neutral axis forming an 

 angle of 90° with the opposite system and an angle of 45° with the axis, just as described 

 by Culmann. The distal part of the horn al)o^'e the core, thus the whole hook, is 

 solid horn, 1)ut tlie sheath sur]'ounding tlie core is oidy weakly de^■eloped. At the tip 

 of the core the slieath is thicker on the anterior side, but Ijelow tlie middle of the core 

 the sheath is thicker ])osteriorly, being ^"ery tliiii on ihe anterior side and measuring 

 at the base hardly 1 mm. or less. The whole organ is, especially distally, strongiy 

 compressed from the sides. The horns are evidently used in the sagittal plane^) and 

 then the compression lurs a. strengthening effect in the plane of attack at the sanie time 

 as material is sa^-ed. The end of the le^'er has, of coiirse, to endure the greatest bi-eaking 

 power and tlie base of tJie core constitutes, to withstand this, a tube which is considerably 

 widened towaxds the place of insertion. This is in accordance witli the rule about placing 

 the resistant material peripherically as far as possible from the neutral axis to obtain 

 the greatest effect The thin svalls are braced ]}\ some osseous iamella?. The recurxed 

 uiicinate tips are probably used as hooks from below upwards. The area of section of 

 the hook is very elongate which is a suitable mechanical adaption but it is a little broader 

 in front than behind and to be perfect it ought to be the contrary. In the straight part 

 of the horn which includes the core the latter gives the most resistance. Its compacta 

 is therefore well developed all the way to the tip especially on the strained (posterior) 

 side. Through the development of Culmann 's trajectories its power of resistance is ettected 

 witli retrenchment of material. On the strained upjier side the elastic element, the liorny 

 sheath, is a, little better develo])cd all along. Tlie liorny matter on the anterior side of 

 tlie oblique tip of the core has an arrangement concordant with the trajectories of pressure 

 (conf. tig. 8). The growth of the horny sheath seems to be periodical to judge from 

 the layers conspicous on the section. 



In lus beautiful work »Kecherches pour servir ;i Thistoire naturelle des Manimiféres» 

 Milne Edwards has tigured sections of liorii cores of ti\e species of Nenior/mcilas. All of 



1) In the book entitled ■ Das Thierleben der Erde- IIaacUxE describes the fight between the males of this 

 species during the rutting season and informs as that the buclis soniotimes »schlitzen ihni { Nebenbuhler •) mit den 

 Krickelspitzen den Baiich öder eiuo andere Körperstelle aufs. This indicates movemeiits from below and upwards. 



