Absorption of Cosmic Rays in the Milky Way.

-Two of the elements of the tarsus are illustrated in plate 1, figures 3 to 4b. The astragalus and calcaneum resemble the corresponding bones in Leptoreodon graciiW Scott. Concluding RPmarks.-Hesperomeryx edwardsi is more closely related to Leptoreodon than to Leptotragulus. It differs from Leptoreodon marshi and from L. gracilis in certain features of the dentition regarded as of subgeneric rank. Hesperomeryx appears to be in slight measure at least, more advanced than the species from the Uinta. Among the later Eocene Artiodactyla, Leptoreodon is unique in the advanced character of the upper molars. This genus is obviously a leptomerycid, but I am not aware of any lower Oligocene genus sufficiently close to it to be regarded as a direct descendant. The oreodonts of the Sespe Eocene show a development quite distinct from that of Hesperomeryx. The cleft between the latter form and the oreodonts unquestionably extends farther back in the Eocene.