310 
3. Another skull of the same species showing the part 
anterior to the bifurcation of the sagittal crest. 
4. Another large skull of the same species, wanting the 
greater part of the face. 
5. A nearly complete skull of another species. 
6. The greater part of two skulls of Oveodon Culbert- 
soni (the original and typical species), smaller than any 
of the above. 
7. Half of the frontal region of an individual larger 
than any of the others. 
8. Casts of the brain of a large and of a small species, 
with determinable parts of bones attached. 
9. Many pieces, more or less complete, chiefly parts of 
upper and lower jaws with teeth, including a number 
which show the canine and incisor teeth. 
10, Portions of limb bones, and a number of vertebrze. 
Besides these, the collection includes Carnivorous, 
Rodent, and other very interesting remains, 
“The deposits of the Mauvaises Terres,” seys Prof. 
Leidy, “are remarkable for the great quantity of fossil 
remains of mammals and turtles they have yielded with- 
out further exploration than picking them up from the 
surface of the country. Detached from the neighbouring 
soft and readily disintegrating rocks, the fossils lie strewn 
about, and have often attracted the attention of the least 
curious of those who have traversed the district. Many 
of the loose fossils have gradually been collected by tra- 
vellers and others, so that few of a conspicuous character, 
I am told, now remain. Of those collected, by far the 
greater part have been submitted to my investigation, 
and these have amounted to the enormous quantity of 
between three and four tons in weight.” The first descrip- 
tion of fossils from the Mauvaises Terres, was by Dr. 
Prout, who, in 1846 and 1847, described a jaw of a large 
animal supposed to be a Paleotherium, in the American 
Fournal of Science and Art. Gradually specimens came 
to light, many of which were described by Prof. Leidy, 
who collected and completed his descriptions in 1852, 
when he published, in the Smithsonian Contributions, 
“The Ancient Fauna of Nebraska,” of 126 pages, and 24 
splendid plates. In succeeding years the Mauvaises Terres 
were further explored by Dr. David Dale Owen, Dr. John 
Evans, and Dr. F. V. Hayden, who brought to Phila- 
delphia large collections of fossils. Altogether Prof, 
Leidy supposes that he has seen entire skulls or portions 
of skulls of about 500 individual Oreodonts, a very large 
proportion of which belong to one species, Oreodon Cu/- 
bertson?, In 1869 the results of his twenty years’ labour 
were published as the seventh volume of the second series 
of the “Journal of the Academy of Natural Sciences of 
Philadelphia,” under the title of the “ Extinct Mammalian 
Fauna of Dakotah and Nebraska,” 472 pages, and 29 
plates, large quarto. This great work includes also a 
synopsis of the entire mammalian remains of North 
America, with the most complete references and the 
author’s valuable critical opinions. The interest is not 
merely in the artiodactyle ungulates, but also in the 
perissodactyles, including the famous Hipparion and 
Anchitherium, as well as the Rhinoceros, Machairodus, 
Mastodon, and Edentate remains. Quite recently Prof, 
Marsh has described a new medium-sized species of 
Oreodon in the current number of the American Fournal 
of Science and Art. 
The family Oreodontidz is characterised by the 
possession of an elongated massive skull, of which the 
portion in front of the articulation of the lower jaw con- 
stitutes more than three-fourths. The upper surface 
slopes gradually from behind forwards. Posteriorly is a 
high sagittal crest (I}in. at the greatest height in large 
species), reaching far back, so as to project on a level 
considerably behind that of the occipital condyles. The 
crest is flanked by large and wide temporal fossze, their 
floor being chiefly formed by the squamous bone, which 
1s internally strongly convex, and bears a blunt ridge 
NATURE 
| Aug. 14, 1873. 
proceeding from behind forwards, downwards, and out- 
wards. The sagittal crest bifurcates anteriorly to form 
the postero-lateral sides of a nearly flat lozenge-shaped 
frontal region, whose lateral angles overarch the com- 
pleted bony orbits. The upper surface of the face is 
terminated by elongated convex nasals, which extend, I 
think, quite to the level of the front of the premaxilla, and 
project further in the middle line than at the sides. The 
nasal cavities are very large, high at the anterior opening, 
and do not open laterally on the face near the orbit, 
They have complicated turbinals. The frontal region is 
alternately gently convex and concave, being more 
convex near the lateral angles. The frontals have, near 
the middle line on each side, a considerable supra- 
orbital foramen, appearing at about the level of the 
posterior boundary of the orbit. 
On the lateral aspect of the skull there is first to be 
noticed the lateral occipital crest which extends out- 
wards and backwards, as the outer margin of the post- 
occipital fossa, which varies in size. It then bifur- 
cates, giving an inferior branch continuing the margin of 
this fossa, and a lateral branch which passes far out- 
wards, bounding the great temporal fossa. This ridge 
rises higher as it recedes from the occipital region, and 
external to the articulation of the lower jaw developes 
into a curved crest, which is remarkably large and thick 
in one specimen. Further forward this crest does 
not exist. The widest part of the skull is just in front 
of this; in one of our species the width at this point 
is twice as great as the distance from the occipital 
to the orbit. The zygomatic process of the squamosal 
comes forward to the under part of the orbit, and is 
received into a long concavity of the malar. The latter 
passes above this process, to join the post-orbital process 
of the frontal, and bound the large oval or circular orbit. 
The malar is often of great vertical depth, and joins a pro- 
minence of the maxillz above the alveoli of the posterior 
molars. Inside and above this elevation, the lachrymal 
occupies a considerable space on the face, and has an 
antorbital fossa of varying size. Anteriorly the face 
continues comparatively high, generally convex, and 
nearly vertical. 
The base of the skull presents the occipital condyles, 
which have their anterior and posterior portions obliquely 
bent upon each other at an acute angle; they approach 
very close to one another in the median line below. The 
basi-occipital has a strong raised median ridge, which 
gradually dies away on the basi-sphenoid. The basi- 
cranial axis is set at an angle of about 4o° to the palatine 
axis. Externally there is a large nipple-shaped post- 
glenoid process of the squamosal (the transverse diameter 
being the greater). Immediately on its inner side is a 
large auditory bulla, somewhat compressed ; and applied 
to its external surface, and at the same time nearly 
touching the post-glenoid process is a long and strong 
paroccipital, The external meatus opens obliquely up- 
ward in front of the paroccipital. ‘ 
Between the teeth, the palate is of almost uniform 
width, is regularly concave, and smooth. It extends for 
some distance behind the molar teeth, being narrowed ; 
and has a concave posterior margin of different form in 
the various species. The pterygoid continues the lateral 
part of the concavity to the alisphenoid region, 
The horizontal ramus of the mandible is of moderate 
height, each half being separated slightly from the other 
in the specimens. The symphysis is considerable, and 
shows serrated sutures. The anterior end of the mandible 
is very little diminished in height, has less of the spatulate 
form than ordinary ruminants, and is somewhat expanded 
in consequence of the size of the canines. The rami are 
very nearly parallel throughout their whole extent. The 
ascending ramus is high, with a small coronoid process, 
and a transversely elongated condyle. ; 
The dental formula is— 
