32 Einar lönnberg, studies on ruminants. 



truding- sinuous ;ind hoUow base of the core. In the musk-ox there is at an early stage 

 a kind of horny cap formed, but this one covers solid frontal exostoses, which låter on 

 are reabsorbed and substituted by a- solid horny niass svmk down in the bony tissue. 

 There is thus no genetie connection between these two kinds of horns, biit only a 

 parallelisin, to a eertain degree. The liorns of the nuiskox show just as little affinity 

 in structure to the same organs in the genus Bos aiid differ likewise in an essential 

 degree from those of Ovis and Capra, as will be proved in the following. 



In the next subfamily Caprino' the horns have quite a different fnnction than in 

 the foregoing, as will be pointed ont presently. In consequence hereof the structure is 

 different as vvell with regard to the core as to the sheath. I have made the horns of 

 the common sheep objects for my investigation as a type for the genus Ovis. In such 

 a horn of normal size and development the bony core forms a more or less complete 

 halfcircle and is compressed laterally. In the base is found a rather large sinus, a con- 

 tinuation of the frontal sinus, which occupies, in the specimens at hand, about two sevenths 

 of the axial lenofth of the core. The walls surroundino- this sinus have a rather dense 

 and firm structure without deserving the name of compact. This firm, lougitudinally and 

 finely tubular spongiosa eontinues in distal direction so as to form a peripheric layer all 

 över the core and is especially well developed on the concave side of the core, less so 

 on the convex one. The iiitei-ior of the core is formed by a coarse partly tubular spongiosa 

 with rather wide interstices a}id canals but thin osseous ]amella\ Especially in the distal 

 pai't of the coi-e the tubes and canals are seen to open at the surface of the convex side. 

 On the lateral and medial surfaces, too, some openings are seen, but none on the concave 

 one. The structure of the core can thus be termed wea,k, as there is neither any quite 

 compact bony tissue nor mechanical arrangements in the form of Culiviann's trajectories 

 etc. It thus difters from the core of the antelopes as well as from that of Ovihos. It 

 is in large horns comparatively short, but not so short as in the muskox. The horny 

 sheath is transversally wrinkled all round. It is comparati\'ely loose in its structure and 

 therefore the surface of the dead horn beconies sometimes lameilar. The horn ends with 

 a quite blunt tip. Tiie horn is conqjressed laterally in such manner that it becomes 

 more or less triangulär in section. The base of the triaiigle then corresponds to the 

 convex surface and the point to the concave one. The former convex side of the horny 

 sheath is very nuich thicker than the mesial and latei'al ones and even thicker than the 

 concave side although the latter, at least sometimes, is braced by a, considerable horny 

 ridge. The sheath is com])ai'atively thick and might give the oi'gan its inain strength. 

 The whole arrangement of the material as well as the shape of the horn reminds one of 

 a curved T beam. It is thus evident that the horn of the sheep is strengthened in ordt'r 

 to withstand shocks in the sagittal plane or a breaking force working from tlie anterior 

 (convex) side in a direction towards the posterior (conca,ve) side. In such a case the 

 anterior (convex) side is stretched and the ])Ost(M'ior (concave) One pressed. It is con- 

 sequently then proper that the elastic hoi'ny matter is thicker on the former, l)ut that the 



') It is possible, luiwover, th;xt the nieinbers of the gcims UnnitruijuH miglit use the sharp points i>f their 

 comparatively short lioriis in the same way as the antelopes aml not only the anterior ridges of the comijressed 

 horns a other "'oats. ,,, . 



