October i, 1891] 



NATURE 



525 



circumstance that they indicate the existence of an animal 

 to a great extent intermediate between the giraffe and 

 the following genus. 



The genus Helladotherium was established upon the 

 remains of a large giraffe-like ruminant from the 

 Pikermi beds of Greece, to which a skull from the Indian 

 Siwaliks, which had been previously regarded as referable 

 to the female of Stvat/teriin/i, proved to belong. The 

 Helladothere, of which the entire skeleton is known, was 

 a hornless animal, of larger size than the giraffe, but 

 with much shorter and stouter neck and limbs. The 

 skull approximates in many respects to that of the giraffe, 

 having the same long parietal region, but with a minor 

 development of cells in the frontals, and the important 

 difference that there is no unossified space below the eye. 

 The limbs agree with those of the giraffe in the great 

 relative length of the anterior pair, as is shown by the 

 radius being considerably longer than the tibia. That 

 the Helladothere was not the female of the Sivathere 

 seems to be evident from the absence in the Pikermi 

 beds of the antler-like cranial appendages of the latter, 

 which are comparatively common in the Indian Siwaliks. 

 The intimate affinity existing between the Helladothere 

 and the giraffe has been admitted by all who have written 

 on the subject. 



The animal recently described by Messrs. Rodler and 

 Weithofer from the Persian Pliocene, for which the 

 hybrid name Alcicephalus has been proposed, tends to 

 connect the Helladothere with the deer, and more es- 

 pecially the elk. Thus, in the first place, the front and 

 hind limbs are approximately equal, the length of the 

 radius and ulna being nearly the same. Then, again, 

 from the total absence of air-cells in the frontal region of 

 the skull, the middle of the face is nearly flat, and the 

 orbits have their frontal borders in the plane of the face, 

 instead of considerably below it, as in the Helladothere, 

 and still more so in the giraffe. There is, however, no 

 unossified space in front of the eye ; although the whole 

 contour of the skull is strikingly elk-like. 



The conclusion to be drawn from these hornless forms 

 appears to be that they serve to connect the giraffe with 

 less aberrant ruminants, and more especially the Cervidce, 

 and also that the unossified vacuity in the skull of the 

 giraffe is probably an acquired feature, since it is absent 

 both in the extinct giraffoid genera, and in the earliest deer, 

 like the Miocene Ainphitragulus. Both giraffes and deer 

 may, therefore, probably have had a common ancestor 

 more or less closely allied to the lower Miocene genus 

 Gelocus. 



Leaving now these hornless forms, as to the affinities 

 of which there has been no dispute, we have to turn our 

 attention to another group provided with cranial append- 

 ages of very curious and still imperfectly understood 

 structure, in regard to whose relationship exceedingly 

 different views have been entertained. This group, so 

 far as we know at present, seems to be confined to the 

 Pliocene of India and Persia, being represented in the 

 former area by the gigantic Sivatherium, Braviatheriuui, 

 and Hydaspiiherium, and in the latter by the much smaller 

 UnniatheriwH. In all these animals the skull is cha- 

 racterized by the extreme shortness of the parietal region, 

 and the position of the horns or antlers immediately over 

 the occiput ; the elevated facial profile thus produced being 

 in very striking contrast to the straight one of the deer. In 

 Bramatheriuni and HydaspHherium the cranial append- 

 ages rise from a massive common base, and the latter 

 genus is distinguished from all the others by the presence 

 of an unossified space below the eye, corresponding to 

 that of the giraffe. Their molar teeth are very similar to 

 those of the Helladothere. In the Sivathere, on the other 

 hand, there is one pair of large branching and palmated 

 cranial appendages rising from separate bases imme- 

 diately above the occiput ; and in addition to these a pair 

 of much smaller conical ones placed immediately over the 



NO. I 144, VOL. 44] 



orbits. In general appearance the large palmated append- 

 ages are more like the antlers of the elk than those of any 

 other existing ruminants ; but the absence of a "burr" at 

 their base indicates that they v. ere not deciduous, while 

 the deep arterial grooves on their surface suggest that they 

 were clothed either with skin or with a horny substance. 

 The molar teeth conform to those of the giraffe— and to 

 a less degree the deer — having the same rugose enamel ; 

 but the ridges on the outer surfaces of those of the upper 

 jaw are more developed than in the other extinct genera. A 

 peculiarly giraffe-like and cervine feature in these upper 

 teeth is the extension of the anterior extremity of the 

 anterior crescent far towards the outer side of the crown. 

 Lastly, the humerus of the Sivathere resembles that of 

 the giraffe in the presence of a double groove for the 

 biceps muscle ; while the form of the terminal bones of 

 the feet is almost identical in the two animals. In 

 the small Persian Urmiatherium, which is known 

 only by the hinder portion of the skull, it appears that 

 the cranial appendages consisted of a pair of unbranched, 

 somewhat compressed, and upright processes rising im- 

 mediately above the occiput. 



With regard to the affinities of this group, it has been 

 argued that the shortness of the parietal region of the 

 skull, and the position of the cranial appendages imme- 

 diately above the occiput, indicate affinity with certain 

 African antelopes, such as the Sassabi and its kindred 

 {Alcelaphus). In that group of antelopes it is, however, 

 perfectly clear that the features in question are acquired 

 ones ; the allied Blessbok scarcely possessing them in 

 any degree. Again, the straightness of the cranial axis 

 in the skull of Waller's gazelle {Gazella ivalleri) shows 

 that the arching of this axis, which is so characteristic of 

 most antelopes, is likewise a feature specially acquired 

 among that group of animals. Moreover, apart from this 

 evidence, no one who thinks for a moment on the sub- 

 ject can believe that the Sassabi, with its narrow sheep- 

 like molars and true horns, and the Sivathere, with its 

 broad giraffe-like molars and cranial appendages, which 

 are neither true horns nor true antlers, can be anything 

 approaching to first cousins ; and yet if they are not so, 

 it is perfectly evident that the similarity in the structure 

 of their skulls must have been independently acquired. 

 It is therefore abundantly clear that no arguments based 

 on these resemblances will hold water ; the true explana- 

 tion probably being that the superficial similarity of their 

 skulls is solely connected with the support of cranial 

 appendages having a similar position in both groups. 



It follows from this that, if a type of skull with a short 

 parietal region, a curved basal axis, and horns placed 

 immediately over the occiput, has been independently 

 developed among the antelopes from a type of skull with 

 a long parietal region, a straight basal axis, and horns 

 placed over the orbits, there is no conceivable reason 

 why a similar line of development should not have taken 

 place among giraffe-like animals. Taking, therefore, into 

 consideration that the Sivathere and its allies have molar 

 teeth like those of the giraffe, that their cranial append- 

 ages could be derived from those of the latter by special 

 modification and development better than from those 

 of any other group, that their humerus has a double 

 bicipital groove, that the terminal phalangeals of their 

 feet are giraffe-like, and that the proportions of their 

 limbs are only a step beyond those obtaining in the ad- 

 mittedly giraffoid Helladothere, the evidence in favour of 

 regarding these animals as greatly modified Giraffoids is 

 so strong as to be almost a certainty. Indeed, it appears 

 most probable that we ought to regard the Sivathere and 

 its allies as holding a somewhat analogous position among 

 the Giraffoids to that occupied among the antelopes by 

 the Sassabi and its cousins. 



The writer has purposely refrained from making any 

 reference to the large unossified suborbital vacuity in the 

 skull of the Hydaspithere, as reasons have already been 



