This group is characterised by the following assemblage of characters. Extinct, often plantigrade Ungulates, with five-toed limbs. Bones of carpus and tarsus not always interlocking, but sometimes lying above each other in corresponding positions. The humerus has an entepicondylar foramen. Dental formula quite complete; the molars brachyodont and bunodont. The premolars are simpler than the molars. The canines are small. As with other early types, the zygapophyses are flat and do not interlock. The astragalus is like that of the Creodonta. This group was American and European in range, the remains of its rather numerous genera being of Eocene time. The best-known genus is _Phenacodus_, of which some account will be given before discussing the, in many cases, more fragmentary remains of other allied forms. The genus _Phenacodus_ was first described so long ago as 1872, from a few scattered teeth. Since then several nearly complete skeletons have been obtained, and we are in full possession of {203} the details of its osteology. It was not a large creature (see Fig. 110, p. 196), about 6 feet in length, with a small head. The feet were more or less plantigrade, and five-toed. The last phalanges of the toes show that they carried hoofs and not claws; yet the fore-feet look a little as if they could be used as grasping organs. The third digit of both hind- and fore-feet exceeds the others, and thus a Perissodactyle-like foot characterised this Eocene creature. The tail is exceedingly long, and must have reached the ground as the animal walked. This is of course by no means an Ungulate character. Still, in the totality of its organisation the animal was decidedly Ungulate, though Professor Cope spoke of _Phenacodus_ as not merely an ancestral Ungulate but as the parent form of Insectivores, Carnivores, Lemurs, Monkeys, and Man himself! The scapula indeed is from its breadth and oval contour rather like that of a Carnivore. The clavicles as in other Ungulates are absent. The femur is Perissodactyle rather than Artiodactyle in the presence of a third trochanter. The creature had fifteen pairs of ribs and five or six lumbar vertebrae. The two bones of the leg which lie below the femur are perfectly distinct and separate. A cast of the brain-case shows that the cerebral hemispheres were smooth and small, the cerebellum of course completely uncovered and nearly as large as the cerebrum. The olfactory lobes were also large. The complete skeleton of _Phenacodus_ has lately been excavated more fully from the enveloping matrix by Professor Osborn,[123] and mounted in what is regarded as the natural position of the beast. It appears that though five-toed it went upon the three middle toes only, and furthermore that of these the middle one was the more prevailing, so that _Phenacodus_ was distinctly "Perissodactyle," at least in habit. Moreover its "long hind-quarters, the long powerful tail ... are reminiscent of Creodont ancestry." The genus was