122 0. C. Marsh—Mammals of the order Dinocerata. 
on the maxillaries were conical, much elongated, and undoubt- 
edly formed most powerful means of defence. The posterior 
horns were the largest, and their flattened cores indicate that 
they were expanded, and perhaps branched. All the horn cores 
are solid, nearly smooth externally, and none of them show any 
indication of a burr. Whether both sexes had horns, cannot at 
present be decided, but this was probably the case. 
e remains on which this description is based are all from 
the Eocene deposits of Wyoming. A more complete descrip- 
tion, with full illustrations, is in course of preparation. 
YALE CoLLEGE, New Haven, Jan. 13th, 1873. 
Postscript. 
Since the above was in type, a short paper by Prof. Cope on the 
same subject, read before the Philadelphia Academy, and bearing 
the date of Jan. 16th, 1873, has been received. The paper Cg on 
e 
mistakes in the paper, among which are the following: Ist. 1e 
genus Dinoceras was not originally referred to the Perissodacty]s, 
d 
5th. The communication I made on this subject before the Amer 
ican Philosophical Society was not Dec. 30th, 1872, but oe 
20th, 1872, Prof. Cope being present. 6th. The nasal bones ™ 
the Dinocerata are not exceedingly short, but much elongated. 
7th. The malar bone does not form the middle element of the 
zygomatic arch, but the anterior, as in the Tapir. 8th. The from 
tals do not have a great prolongation forward, and it is Very 
doubtful if they support horns or processes at both extremities. 
th. The nasal bones are not deeply excavated at their ees 
ties, The assertion that it is “exceedingly probable that the tue 
Yale College, Jan. 21st, 1873. 
EXPLANATION OF PLATES. 
Plate I. Dinoceras mirabilis Marsh. Oblique view. One-fifth na 
diate IT. — mirabilis Marsh. Figure 1, side view; figure 
tural size. 
tural 
‘as ; Si 2, 
gure 3, top view. All one-eighth nai 
size. 
front view ; 
