_The Sabre-toothed Felis_ (_Machairodus latidens_). This animal has usually been spoken of as the cave-tiger, but Professor W. Boyd Dawkins has shown that it was no more closely allied to the tigers than to other felines, and that "the very tempting name of 'sabre-toothed tiger' must therefore be given up as implying a relationship that does not exist. It differs from the genus _Felis_ in the enormous development of the serrated upper canines, as well as the presence of a third lobe on the sectorial edge of the upper premolar." It was a peculiarly destructive animal, its teeth being described as "uniting the power of a saw with that of a knife." The canine tooth of this animal is the most perfect instrument for piercing and dividing flesh known. It belonged to the southern group of mammalia; and, as the winters became cold, it probably migrated each fall. Although it was never abundant it was much feared. Remains of similar animals have been found in the United States mingled with the bones of the mammoth. _Living Species._ Of the living species there were present in mid-Pleistocene times, the brown bear, the grizzly bear, the wolf, the fox, the stag, the roe, the urus or the wild-ox, the aurochs or European bison, the hippopotamus, the horse, the wild boar, the beaver, the water rat, the lion, sometimes spoken of as the cave-lion and being the same species as the _Felis leo_ of to-day, the lynx, the panther or leopard, the wild cat, the spotted hyena, the otter, the musk sheep, and the marmot. No animal was domesticated at this time. _The Urus._ The urus, which is the representative of the wild cattle of this period, is the ancestor of our long-horned cattle, and should be distinguished from the short-horned cattle that appear in western Europe in the prehistoric period in a domesticated state. The wild bulls were formidable antagonists when enraged. It is thought by some that the Chillingham cattle are descendants of the urus. The color of the urus is not known. Some think that it was white, but others doubt that the species would have been able to survive with such a conspicuous covering. On account of their fear of the beasts of prey the wild cattle probably kept under cover of the trees during the day and went out to the grassy uplands only when darkness came on. The feeding grounds of the grass-eating animals determined the haunts of the beasts of prey. When wild cattle are attacked, the larger animals in the herd surround the younger and weaker so as to present a wall of horns to the assailant. This habit is not peculiar to wild cattle, but is quite characteristic of all grass-eating animals.