KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 35. N:0 3. 4^1 ' 



there cannot be developed any true sinus, but other cavities may be formed. When the 

 frontals become more sinuous the cores get larger sinus, too. When the sinus occupy 

 the greater part of the cores there might be need for a bracing of the hollow tube. This 

 is then affected by the development of lameliar trabeculae which just as well as the tra- 

 jectories in the spongiosa are arranged in accordance with Culmann's law, because they 

 aim at the same mark, the strengthening of the core. This arrangement is most simple 

 and therefore most instructive in the core of the goat, but also in a more complicated 

 manner in the common ox, the Indian buffalo and its more primitive relative Anoa in 

 adult stage. A completely hollow core braced by a system of trabecute represents the 

 highest aiid most perfect type of development reached by this organ in the series of 

 Camicornia, because it combines great strength with comparativcly little espeiiditure of 

 material and small weight. 



The solid core, on the other hand, is the most primitive condition, but which also 

 may have been retained by forms which otherwise have been developed in difterent and 

 diverging directions. The presence of a solid core is accordingly no proof of a close 

 relationship. This might be shown by comparing for instance such forms as Cephalophus, 

 Saiga, Cervicapra or Pelea and Tragelaphus. It might easily be assumed that during the 

 development from the most primitive form changes of structure have taken place in the 

 same direction quite independently in difiFerent antelopes which stånd in no close kinship 

 to each other. The mechanical laws are the same for all and may be independently 

 applied by distant forras. There must consequently occur a number of parallelisms which 

 are not genetically connected. Thus, for instance, the horns have become compressed or 

 in other words gained a prolongation of the section in the plane of attack in difterent 

 groups, e. g. Rliaphicerus — Hippotragus. In a similar manner the core in difterent forms 

 has been independently strengthened at the base by a peripherical accumulation of the 

 resistant material, and then siraultaneously the tissue in the centre of the base may be 

 loosened e. g. Strepsiceros — Gazella. This loosening may especially in such cases when 

 the frontal sinuses are large be extended so far as to the development of sinuous cavities 

 in the base of the core e. g. Åntidorcas — Oryx — Rupicapra — Biihalis. The agreement 

 in development and likeness in its result needs not in these cases indicate the same origin 

 or affinity. Rutimeyer's ^) »Gruppe der Gemsen» or »Antilopen mit lufthohlen Hörnern» 

 is therefore an artificial construetion which is not founded on reliable characters when 

 such forms as Rupicajwa — Oryx — Buhalis or Connochcetes are united. Likewise in 

 spongious cores the material may be arranged in trajectories according to Culmann's law 

 quite independently, and as examples of this may be quoted such forms as Rupicapra and 

 Buhalis. Lastly it might be assumed that more or less completely hollow horn-cores may 

 be developed independently, Capra and Bos (with the exception of the African buffalo), 

 and in such cases the walls are braced by lameilar trabecula?. The latter are difterently 

 arranged in goats and oxen, that is true, but this might stånd in connection just as much 

 with the difterent way in which the horns are used by these two groups of animals as 

 depending on difterent origin, although the latter also is probable. 



') »Die Kinder der Tertiärepoche», Ziirich 1877, Abh. d. schwciz. paläont. Ges. Vol. IV. 



K. Sv. Vet. Akad. Handl. Band 35. N:o 3. 



