but in my specimen which is a comparatively young individual, I find a small alveolus for the upper canine, which modifies the formula to 3 1 4 3 -------. 2 1 4 3 In the first upper dentition found, incisors 2 and 3 were represented by alveoli only, but our specimen shows these teeth, and we find that they have enamel only on the outer face, making this genus more specialized in this respect than any of the other typotheres. The upper molars have the deep inner inflexion bifurcated, which makes the tooth three-lobed, a character which grows more marked the older the individual is. The premaxillae are high and bring the snout well forward. The nasals are lacking, but the bounding bones show them to have been unusually broad and flat. The maxilla extends up to the nasals, and bounds the lower border of the orbit, and projects backward in a heavy overhanging zygomatic process. The lachrymal bone is large externally, with a large but low lachrymal tubercle just below which is found the lachrymal duct, opening just in front of the margin of the orbit. The frontals are short and wide, extending outward over the orbit in a strong postorbital process which bounds half of the rear of the orbit. The parietals, meeting medianly, rise in a strong sagittal crest. Unfortunately the back part of the cranium is lacking. From another specimen, which contained the brain cast, it is clear that the bulla was much inflated and hollow, and that there was an inflation in the upper part of the squamosum, as in _Prosotherium_, etc. [Illustration: Fig. 46. E. spegazzinianus—½ natural size.] One specimen with the facial portion badly weathered, but retaining enough to identify the species as _E. spegazzinianus_, preserved the brain case, so that it could be prepared out. The most striking feature of this brain is its relatively large size, _E. spegazzinianus_ being an animal about the size of a sheep, and the brain is as large as that of the sheep, which is in strong contrast to what would be expected of an Oligocene form. Compared with the herbivorous Oligocene oreodont, _Eucrotaphus_, an animal of approximately the same size, this brain is half again as large in every way. A second striking feature is the short compact character of the brain, the forebrain extending only a short distance in front of the exit of the optic nerves, and extending backward so as to cover most all of the cerebellum. Thirdly, the cerebral surface is considerably convoluted, comparable to the convolution of a pig’s brain. These features would indicate a specialization of the nervous system, approximating that of the skeleton, and would indicate that this group had advanced in intelligence and activity beyond the grade of nervous development which is apparent in the contemporaries of the _Typotheria_.