KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 35. N:0 3. 43 



the horns have been curved in a certain inanner, backward or forward, it does not seem 

 probable that tliis curving changes direction during the phylogenetical development, for 

 ontogenetical changes are quite impossible, n. b. under the condition that the horn in- 

 creases by even growth. If the growth is uneven, so that the horn is twisted in a spiral, 

 the point of a curved horn may, nevertheless, become directed diffei'ently in consequence 

 of the rotation. Half a tum of the horny sheath makes an originally forward point 

 directed backwards and so on. Occurences of this kind may be met with frequently 

 among the gazelles and Antidorcas. In the latter species the points of the horns are 

 according to the statements in the literature usually directed inwards, but in the specimen 

 at hand backwards, as is mentioned above. The rotation may take place in difterent 

 directions in different forms. In Antidorcas the horn is twisted in a mesial direction 

 from the outer sidé, but in Antilope the direction of the rotation is the same as in the 

 Tragelaphine group, that is from the mesial side outwards. It is evident that the rotation 

 in both cases must have originated independently from non-twisted horns. It seems 

 namely very little probable that the horns of an animal which have become twisted in 

 one direction may through reversion assume a rotation in the opposite direction, but 

 on the other hand it is a fact that closely related species may be found with the horns 

 more or less spirally twisted in opposite directions. Examples of this kind are offered 

 by Capra hircus {cegagrus) with mesially twisted and C. falconeri witli laterally twisted 

 horns. But one of these forms has not originated from the other, but both from a 

 common stock with indifferent non twisted horns. ■ 



In a similar way it may be assumed as a probability that a horncore which has 

 been specialised in such a manner that its substance has become spongious with a well 

 developed system of trajectories arranged according to the mechanical laws, does not 

 through reversion again become compact. For this reason it might be allowed that the 

 gnu with its almost entirely compact cores with the trajectories comparatively little 

 developed represents an earlier and raore primitive stage ( — although later on specialised 

 in a different manner — ) than the caama with its well developed systeras of trajectories. 

 For the correctness of such an opinion speaks also the fact that the horny sheath of the 

 gnu is thinner and less specialised than that of the caama. The horn of the gnn corre- 

 sponds in almost every respect as an homologon to the distal, that is first developed, 

 curve of the horn of the caama. That both these forms really are closely connected 

 may not be contradicted nowadays, as they have so many important characteristics in 

 common. 



If it is difficult to understand that a once spongious core with trajectories should 

 become compact again, it seems still raore iraprobable that a hoUow core raay through 

 reversion becorae solid again. That solidity and compactness of the core is the primitive 

 condition is proved as well ontogenetically as phylogenetically (compare for instance Anoa). 

 The conclusion may then be drawn that such a solid horncore as that of the Cape buffalo 

 cannot possibly be derived from such a hoUow core as that presented by the Indian buffalo 

 or even hy the fullgrown Anoa. 



One of the most primitive among the known forms which with certainty belongs 

 to the series of Asiatic buffaloes is the extinct Siwalik tamarou, as it has been called by 



