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 but reduced by one premolar at least in the upper jaw. It is very important to notice that the incisors have enamel only on their anterior faces, and that the same is the case with the canines, the slender layer present behind the tooth in Hemiganus having vanished in this later form. The tooth pattern of the molars is like that of Hemiganus. The fore-limb is decidedly Edentate-like; but it is the foot which presents the strongest likenesses to that order. "If an anatomist," remarks Dr. Wortman, "had no other part of the skeleton than that of the foot to guide his judgment, and he should fail to detect a most striking similarity between it and that of the Edentata, especially the Ground Sloths, he would not only lay himself open to the criticism of being lacking in the ordinary powers of observation and comparison, but would be suspected of placing the matter upon a basis other than that established by such a method." It is not certain how many toes upon the fore-limbs were possessed by Psittacotherium, but the close resemblance to Mylodon is indeed striking, the third digit being in both forms the most pronounced. Some vertebrae of this Ganodont have been discovered which do not show the complex articular arrangements of later American Edentates. The sacrum, on the other hand, is very like that of the Sloth, and there is a foreshadowing of the attachment of the ilia to the sacrum by co-ossification which is met with in later Edentates. A still later type is the genus Calamodon, which has been shown to occur in Europe as well as in America. C. simplex was a larger beast than either of the genera that have already been treated of, thus affording another example of the increase in size of later as compared with earlier members of the same group, so pronounced among the Ungulata. The lower jaw has the same massive structure that characterises that bone in Hemiganus and Psittacotherium. There is but one incisor, but the premolar and molar series are complete. The canine is Rodent-like in appearance, being imbedded throughout the greater part of the lower jaw; it evidently grew from a persistent pulp. It is enamelled upon the anterior face only. The premolar and molar teeth are in this genus commencing to lose their enamel, which is distributed in the form of vertical bands, leaving interspaces which are not covered by enamel. These teeth, moreover, are decidedly hypselodont, more decidedly so than in Psittacotherium; they are, when unworn, quadricuspidate, with accessory cusps; when more worn, the teeth