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Show 322 DR. C. J. FORSYTH M A J O R O N FOSSIL G I R A F F I D J E . [May 5, frontalia. It is, however, a well-known fact that in the Giraffe the parietals participate also in the conformation of the horns. In the skull of a very young Giraffe, such as that which is to be seen in the remarkably instructive exhibition in the Hall of the British Museum, it is evident that the pair of horns are not formed alone by the bony processes which are situated partly on the frontal3 and to a large extent on the adjacent parietal region, but that those bones themselves are thrust up, the parietals still more than the frontals. It is not possible to demonstrate with certainty the coronal suture in the cast of the Hydaspitherium skull1. But its comparison with a young Giraffe, and with the so-called skull of Helladolherium from the Siwaliks, which is placed by Riitimeyer himself amongst the Giraf-fidas2, is strongly suggestive that in all three the parietal region has about the same extension and continues in the same direction as the frontal region. The horns of Hydaspitherium, in m y opinion, thus occupy the same position as in the Giraffe-that is to say, on the parietal as well as on the frontal bones, only extending much more forwards than in theliving genus. In spite of the enormous elevation of the bones which form the brain-case, this last in Hydaspitherium is not much shorter than in the hornless skull of the Siwaliks. Similarly I a m inclined to believe that in Sivatherium the parietals also take part in the horizontal covering of the skull, so that the analogy with the G n u and the Bovines, advocated by Riitimeyer3, is not justified. The posterior antler-like pair of horns, according to m y view, evidently arises from the parietals. The anterior pair occupies the same position as the horns of Samotherium, the homology with which is completed by the important fact that we can trace a suture between the anterior processes of Sivatherium and their supporting frontals. The supposition as to the extension of the parietalia in Sivatherium and Hydaspitherium can be definitelv proved only when we are able to trace the coronal suture ; but even if Riitimeyer's improbable view as to the position of the parietalia were right, there would not be, for the reasons given, sufficient grounds for uniting these fossils with some of the Antelopes. Be that as it may, the present exposition of facts corroborates Lydekker's view that Sivatherium and Hydaspitherium are nearly akin to the Giraffe4. - 1 Lydekker was unable to trace the coronal suture in the original. He says in the description of the skull of Hydaspitherium megacephalum in question (Indian Tertiary and Post-Tertiary Vertebrata, vol. i. 1880, p. 163):-" Above the occipital crest the common base of the horn-cores rises almost vertically, somewhat after the manner of the iutercoronal ridge of the oxen. It is impossible to say how much of this portion of the cranium is formed by the parietals and how much by the frontals, but I am inclined to think that in the middle line the parietals formed a very narrow strip as in the true oxen." 2 L. c. pp. 74-78. 3 L. Rutimeyer, ' Beitrage zu einer natiirlichen Gesehichte der Hirsche,' i. pp. 80-81. 4 As to Vishnutherium, from the Siwaliks, described by Lydekker, I have no new observations of m y own to offer, but I completely share Lydekker's views as |
