TTA GEOLOGY. 
of the upper jaw (premaxillary bone); there is no canine, and 
the molars are few. The incisor is shorter than in the mastodons, 
etc., and is compressed, trenchant, and recurved, forming a most 
formidable weapon. The great peculiarity is seen in the structure 
of the molars, which is nearly that of Bathmodon Cope, an allied 
Perissodactyl. This type is, however, graded into an approach to 
inotherium in another Perissodactyl, Metalophodon Cope, of 
which more below. 
The type species of this group, called by Prof. Cope Eobasileus 
cornutus, is as large as the Indian elephant, but stood lower, hav- 
ing proportions more like the rhinoceros. The elongate form of 
the cranium Added to this resemblance. The physiognomy was 
very peculiar. On either side of the front, above each orbit, rose 
a stout horn, its base continuous with that of its mate. The 
immensely prolonged nasal bones overhung the premaxillary, as 
in the rhinoceros, and supported on each side near the extremity 
a massive reverted shovel-shaped protuberance, which united at 
an open angle with its fellow on the middle line in front. 
These beasts must have lived in herds, like the elephant of 
to-day, judging from the abundance of their remains, no less than 
twenty-five or thirty individuals having left their bones within 
a short distance of one of the camps of the party. Three species 
were distinguished: E. cornutus, E. furcatus, and E. pressicornis. 
_ The resemblance of the tusks to canine teeth is such as to have 
induced a late author to have based the description of a supposed 
carnivore of large proportions on one of them. 
Tur ARMED MeraLopnopon.—This is an extinct odd-toed ungt- 
late discovered by Prof. Cope in the lowest or ‘ Green River” 
division of the Eocene of Wyoming. The only species found was 
named M. armatus. It possessed a full series of six superior inci- 
sors, and had a formidable knife-like canine, with cutting edges and 
a groove on the outer face. The premolars are like those of Bath- 
modon, i. e., with one outer crescent, while the molars differ in 
having the constituent crest of the single crescent separated on the 
inner side of the tooth, thus producing two subparallel crests. 
The lower premolars are singular in possessing one crescent, witha 
rudimental second by its side. This increases in proportions on 
the posterior teeth till on the last inferior molar the two are nearly 
equally developed. Alternate ridges are however on this tooth 
