MAUVAISES TERRES. 199 
calcareo-siliceous marl, that occupies a higher level, forming part of No. 8, as ex- 
hibited in the Section showing the different beds which compose this eocene tertiary 
formation. These belong chiefly to those lost races of ruminating pachyderms, 
some of which are remarkable for the continuity of the whole range of grinders, 
canine, and incisor teeth; having a scarcely greater interval between the different 
sets than man himself. 
Some of the specimens obtained in this bed are in a good state of preservation, 
and exhibit the whole range of molars, both in the upper and lower jaws, as well 
as the upper and lower canine teeth. : 
The structure of the grinders of some species indicates that they may probably 
be referred to that species of ruminating pachyderms established, by Dr. Leidy, 
under the name of Oreodon Culbertsonii. Others appear to belong to genera and 
species not heretofore described, but belonging to the same family of ungulate 
ruminants. 
One of the most perfectly preserved skulls in the collection, and the one next-in 
size to the Paleotherium Proutii, is a new species of Rhinoceros, belonging to 
Kaup’s subgenus of hornless rhinoceros, Acerotherium (Table IX., Fig. 1); the cra- 
nium of which measured over sixteen inches in length, without the terminating por- 
tions of the nasal bones, which were deficient. The structure of the molar teeth of 
the upper jaw of another specimen, belonging to the same subgenus, approaches some- 
what to Rhinoceros liptorhinus, though sufficiently distinct in the disposition of the 
cusps and lobes, so that Dr. Leidy has described it, in his accompanying memoir, 
under the name of &. Nebrascensis. A view of the whole range of molars and pre- 
molars of this fossil is seen in Fig. 6, on Table XIL., A., engraved from a daguerreo- 
type, reduced nearly to one-fifth the size of the original. Two other skulls, deficient 
only in the anterior part of muzzle, display the molars and premolars in an excellent 
state of preservation (Table X., Figs. 1, 2, and 3; and Table XI., Fig. 2). They be- 
long to a new genus, heretofore alluded to, partaking of the characters found in the 
Hyracotherium and Cheropotamus ; animals, which, though they were much larger, 
bore considerable resemblance to the living babyroussa and peccary. 
Amongst the unique assemblage of extinct pachyderms, this Survey has furnished 
but one specimen of a truly carnivorous type of animal, with prehensile claws ; and, 
I believe, the collections subsequently made by Mr. Culbertson, in the same field, 
furnishes no further example. It is a portion of a fossil skull, referable to that 
remarkable genus of fossil Felidx, the Machairodus or Felis Smilodus, from Brazil ; 
unfortunately, it is in a worse state of preservation than most of the other speci- 
mens of the collection. Its profile is engraved on Table XII, A, Fig. 5, from a 
daguerreotype, reduced nearly one-half from the original. 
Besides these various remains of singular forms of mammiferz, there were also dis- 
covered many turtles, reduced figures of which are given on Table XII, and Table 
_ XIL, A, Figs. 1, 2, 3, 4, and Table XIL., B, Figs. 1 and 2; some of huge dimensions. 
The largest which we were able to transport, and which is represented (Table XIL.,, 
Figs. 1 and 2) two-fifths the natural size, measured sixteen inches by thirteen and a 
quarter, and weighed upwards of fifty-eight pounds. But others were seen, which, 
with the means at command, it was impossible to remove, estimated to weigh a ton. 
