The premaxilla bone in _Pyrotherium_ is crowded out, so that it makes no part of the palate, which is a character of elephants, and in contrast to toxodonts or other groups which have been mentioned. There are two antorbital openings as in elephants, and a feature not common, though not unknown. On either side of the brain case are cellular spaces with intercellular lamellae, which are so characteristic of elephants; a confirmatory feature, though in itself not conclusive. The foramena on the base of the cranium are similar to those on the base of the cranium of elephants, though there are some variations, as for instance, the exoccipital foramen, is isolated in _Pyrotherium_, but fused with the posterior lacerum foramen in elephants, and other slight variations in position; but, on the whole, the foramena of _Pyrotherium_ are much closer to those of elephants than of any other group. There is also much in common with toxodonts and with hyracoids, as would be expected if they have a common ancestry. There is no suggestion of a marsupial arrangement as would be necessary if related to _Diprotodon_. The atlas of _Pyrotherium_ is peculiar in having a marked hypophysis which is unusual, but is a feature of the atlas of _Palaeomastodon_ and _Moeritherium_. The axis is peculiar in that the odontoid is flattened on the upper side and very short and wide. In this the form is unique. The continuation of the articular surface on the lower side of the odontoid with the articular surfaces of the ant. cotyles is a feature also of elephants. The remaining cervicals are greatly shortened almost to plates, which is elephantine again, though this short neck is approximated by _Diprotodon_, some Amblypods and _Arsinotherium_, so that it must be in general looked upon as an adaptive feature, though in its detail it shows again an elephant character. The upper members of the limbs are longer than the lower, which is common to many massive animals. The humerus is tremendously flattened from front to back, even more so than in any of the animals used for comparison, though flattening is a feature of them and of the elephants the most so. With the flattening, the deltoid ridge is prolonged enormously making a crest along the outer side of the bone, which at the lower end rises in a prominent process, as in elephants (also in _Diprotodon_ but in this case the rest of the bone is very different). In addition to this, the supinator ridge is prolonged upward until it almost meets the deltoid, ending in a sharp spur at the top. This spur is more marked in _Pyrotherium_ than in elephants, although they show the same development of the supinator ridge.