16 ■ EINAR LÖNNBERG. STUDIES ON RUMINANTS. 



(originally) ;xntei'o-medial (distally more or less lateral) knob which latter is inove strongly 

 developed. Sometiraes l)oth systerns are united to simple transverse rings and sometimes 

 they alternate, but in all cases they increa.se the strength of the sheath. The cur\ing of 

 the horn, also lessens its risk of breakage and torsion. The place A\hich is inost exposed 

 to breakage, naniely the base, is strengthened by enlargement of the area of section. 



With regard to such beautifal horns as those of the palla-h their importance as orna- 

 ments cannot be denied, bvit this question does not belong to this chapter. Ornaments 

 of this kind being weapons at the same time need, howe^^-er, mechanical arrangements so 

 that they may not be too easily broken and it is these that have been considered here. 



Of the genus Gazella I have had material from two specimens. One of these Avas 

 labelled Gazella r/orcas, the other was not determined. It is provided with slender, almost 

 straiglit (177 mm. in length) horns the tips of which are curved inwards a little and may 

 represent a female specimen of the same species. The horny sheath of the latter ha.s on 

 its anterior and median side annular thickenings ^vhich laterally and behind are less 

 consiDicuous, although not quite missing. The sheath is thickest in front. The core extends 

 through 62 % of the entire length of the horn. It is considerably compressed from the 

 sides, the diameter of the base being in the sagittal plane 16 mm. but in the frontal 

 (transversal) one only 13 mm. The section is also ovnte with the broad end posteriorly. 

 Both these features indicate a tendency to strengthen the core in the sagittal plane and 

 to do this with retrenchment of material. For the same purpose serves also the arran- 

 gement of the material in the base of the core, as will be seen. The base of the core, 

 the end of the lever, which has to resist the greatest breaking power is also more strongly 

 liuilt thau the distal parts which are more or less protected liy tlie horny sheath. There 

 is namely at the base a comparati^^ely thick layer of compact bony tissue. Posteriorly 

 this layer occupies fnlly one fourth of the core, but is much narrowed on the sides, then 

 again becoming thicker anteriorly. These compact walls are soon getting thinner in a 

 distal direction. The central portion of the basal core between these compact layers is 

 taken up by an irregular spongiosa with large meshes. This tissue extends, however, 

 only through the basal fifth of the core and is well detined from the other parts. The 

 greatest part of the core, with exception of the basal region, just described, consists of 

 spongious bony tissue in which the elements are longitudinally stretched in sucli a way 

 that it gets a more or less decided tul^ular appearance. The »tubular» structure is finest 

 in the a.nterior half ■where it gradually, in a distal direction, more and more substitutes 

 the basal compacta,. The compact layer becomes, namely, distally, very thin. Posteriorly 

 and distally the >^tubular» spongiosa is much coarser, and some rather large canals for the 

 main trunks of blood\essels traverse the whole core in a straight line in, and a little 

 behind, the centre and open at the distal tip. The tubular structure of tlie spongiosa is, 

 of course, a suitable arrane-ement sivino- more streno-th than if the spono-iosa had been 

 irreo'ular, and consumino- less material tlian if the core had been solid, llie horns of the 

 ma-le Gazella, dorcas are built after the same type although larger. The horns are curved 

 backwards with the tips again recurved upward or forward. There are annular thickenings 

 in front and on the median side. These are most regular and strongest anteriorly. On 

 both sides tlie regularity is less pronoimced. Often the connection with the lateral parts 



