[Footnote 3: This species is respectfully dedicated to Dr. Joseph
Leidy, of Philadelphia. The specimens upon which it is established
were found on Dry Creek plateau.]
Established upon a head and nearly perfect skeleton of one
individual, and parts of two more.
In this species, as in most others of the sub-order, the nasals are
of immense length and thickness; they overhang the anterior nares,
and project considerably beyond the premaxillaries; they form more
than half of the entire length of the skull, articulating with the
frontals somewhat behind the orbits; the median suture is distinct
throughout. Instead of having an expanding shovel-shaped forward
projection, as in _Loxolophodon_, they narrow from the median osseous
projections (horn cores?) anteriorly. Above the muzzle they are
strongly curved from side to side, on their upper surface forming
a continuous arch; on the under surface of each bone is a deep
concavity, separated from its fellow by the sutural ridge, which
disappears forwards, near the extremity. On the upper surface of each
nasal, near the forward end, is a large osseous tuberosity which is
directed forwards and outwards; these processes are much smaller than
the corresponding ones in the _Loxolophodon_, while they are larger,
of different shape and direction from those in _Dinoceras_. In this
species they are divided throughout by a deep median groove, which
anteriorly becomes a fissure, and separates the extremities of the
nasals completely. In front of these tuberosities, the nasals taper
very rapidly, and end in sharp points which project downwards and
forwards; this portion of the bones is shorter, sharper, and projects
more decidedly downwards than in _Dinoceras_. Above and slightly
behind the sockets of the cranium, the nasals and maxillaries give
rise to the median pair of osseous projections. These are very
large, subtrihedral at the base, and project upwards, outwards, and
strongly forwards. They differ from the corresponding processes
in _Dinoceras_, in their forward projection, in being longer and
more everted, and in their approach to each other at the base. They
taper quite regularly from base to tip, but do not come to a point;
a section here would be subcircular. They are not so long and are
not knobbed at the ends as in _Loxolophodon_. Their inner curve is
convex, the outer concave; converging below at an angle of 90°, they
are united by a strong ridge, which is raised decidedly above the
surface of the nasals. At their posterior insertion they touch the
frontals, lachrymals, and malars. It is probable that the nasals
send up processes on the internal and posterior side of these median
projections; the sutures between these and the maxillary portions are
marked by slight ridges.
_Frontals._--In our specimen it is very difficult to determine the
exact relations of these bones. The nasals narrow at their posterior
end, and articulate with the frontals by a V-shaped suture which
thus encloses them on each side. It is probable that the frontals
run to some point between the posterior or parietal projections. If
we have discovered the suture, they overlap the parietals, sending
up V-shaped processes, which join the sides of the posterior cranial
projections, and form a deep concavity with them. They constitute a
large part of the interior wall of the orbit, but have no postorbital
processes; the superciliary ridge is very strong, and gradually rises
into a large rounded crest, which joins the posterior projection.
The frontal eminences are large, and situated immediately over the
lachrymals. The upper surface of the frontals is marked by two high
ridges, which probably represent the divided parts of the sagittal
crest; they rise from the anterior margin of the bones, and are
strongest above the frontal eminences. They converge, and then
diverging, together forming an X-like curve (without crossing,
however), gradually disappear posteriorly. These various ridges form
four deep concavities on the upper surface of the skull: (1) The
largest already mentioned, between the parietals and the posterior
part of the frontals; (2) that marked by the suture between the
nasals and frontal, not so large; (3 and 4) two much smaller lateral
ridges between the sagittal and superciliary ridges. This great
irregularity of the upper surface of the head is, so far as is yet
known, peculiar to _Uintatherium_.
_Parietals._--The peculiar feature of these bones is the huge pair
of projections (the so-called "posterior horn cores") to which they
give rise. The outer margin of these processes is nearly straight;
the inner margin for its upper two thirds is also straight, the lower
third curving in a high strong ridge to meet its fellow. The anterior
face is rounded and produced into the long crest of the frontals,
while the posterior face is flattened and produced into a similar
but shorter and higher crest which joins the supra-occipital. At the
base of these processes their greatest diameter is fore-and-aft,
while at the top it is transverse. They project upwards and outwards,
but are not curved as in _Dinoceras_, nor are their upper borders so
much arched. Their greatest diameter at top is at right angles to
the corresponding measurement in this last-named genus. Behind the
ridge which connects these projections, the parietals curve sharply
upward to a high occipital crest; between which and the projections
they form a deep basin whose floor is raised above that formed by
the frontals immediately anterior to it. This arrangement differs
from that of both _Loxolophodon_ and _Dinoceras_, especially from
the latter. The temporal fossæ are of great length, deeply concave,
but rather low from above downwards, formed almost entirely by the
parietals, and bounded posteriorly by a sharp outward curve of these
bones. They are of about the same proportionate length, but higher
and very much deeper than in _Loxolophodon_; and are not nearly
so long as in _Dinoceras_, in which genus the parietals expand
far behind the horn-like processes. In our specimen the posterior
part of the fossa is pierced by numerous small venous foramina,
and corresponds precisely in every way, save that of size, to the
specimen figured by Dr. Leidy. (Cont. to Extinct Vert. Fauna, Plate
XXVI., Fig. 1.)
_The Squamosals_ are large and heavy but encroach little upon the
temporal fossæ; they are situated directly below the large parietal
projections. The glenoid cavity is transverse and straight in this
direction, broad and shallow, with no internal process; and the
post-glenoid process is long and massive. The zygomatic process is
short, stout, high, and trihedral, with a strongly arched upper
margin. The articulation with the malar is by a straight, flat face,
and anchylosis of the two never takes place. The anterior termination
is pointed, and the outer margin is rounded.
_The Malars_ form none of the face. They are long, slender, curved
downwards and backwards, and but little outwards. They are longer,
straighter, and less curved outwards than in either _Loxolophodon_ or
_Dinoceras_; they do not present the sharp angle in the lower margin
shown in the latter genus, nor are they so extensively overlapped
by the zygomatic processes of the squamosal. Posterior to the molar
series, the malars are greatly compressed and very slender, but at
the junction with the maxillaries they become much wider and thicker.
There is no trace of a postorbital process; and the projections from
the under surface of the bone at their junction with the squamosals,
so prominent in Dinoceras, are here rudimentary or absent. As a
whole, the zygomatic arch is very long, slender, simple, curved
upwards and very slightly outwards, so slightly that it is completely
overhung by the superciliary ridge and frontal crest.
_The Lachrymals_ are unusually large, and form the anterior part of
the orbit; they encroach considerably upon the face, and articulate
with the superciliary ridges above. The lachrymal foramen is very
large.
_The Maxillaries_ are of great length, being nearly as long as the
nasals. They extend somewhat beyond the last molar; but the suture
between them and the pterygoids is very obscure. There is a very long
diastema between the canine and molar series, and the lower margin
is arched upwards; above this, between the orbit and the socket of
the canine, there is a large, deep fossa, but we can discover no
infraorbital foramina. The sockets of the canines are very large
and prominent, they curve upwards and backwards to the base of the
median cranial projections, but these are not excavated to receive
them, as is the case in _Dinoceras_. The most peculiar feature of the
maxillary bones is the pair of large horn-like projections, to which,
in conjunction with the nasals, they give rise. These have already
been described, and it only remains to add that they correspond in
position to those of _Dinoceras_, and are therefore much further
forward than those of _Loxolophodon_.
The palatine plates of the maxillaries are long and very narrow; they
are concave transversely, and are separated from each other by a high
median ridge. The posterior palatine foramina are small.
The _Palatines_ are very short, narrow, and concave, and are
separated by a ridge. They are considerably excavated on the
posterior border, in this respect differing from _Loxolophodon_.
The _Pterygoids_ and the pterygoid plates of the alisphenoid are
compressed; the former join the alveolar borders of the maxillary,
which are produced somewhat beyond the last molars. The alisphenoid
canal is very large, but rather short.
The _Premaxillaries_ are of very peculiar shape, somewhat like
a _u_, with one side--the lower--the longer. The upper portion
articulates with the nasals, running along the narial opening to
about three inches from the angle; the free portion is short,
slender, and tapering; it is curved downwards and slightly inwards;
the premaxillaries do not meet, leaving the incisive foramen
unenclosed, and are edentulous. At the end of the upper portion there
are prominent processes for the attachment of the muscles of the
proboscis, which probably resembled that of the tapir.
The anterior narial opening is very large, but is considerably
concealed by the overhanging of the nasals. There is no osseous
septum between the nostrils. The posterior nares are much smaller,
being especially contracted in width; it is divided above by the
_Vomer_, which is very short, and does not reach the palatines. The
nasal cavity thus formed is long, straight, and gradually narrows
backwards.
Of the Mandible we have but a small portion of the right
ramus, comprising the part opposed to the upper canine, from
the dental canal downwards. The jaw at this place has a large
downward-projecting process, very similar to that figured by Marsh
in his plate of _Dinoceras laticeps_. This process curves slightly
outward, and has its external side convex in both directions, and
its internal side convex fore-and-aft, concave from above downwards.
The posterior mental foramen, which is the only one preserved in our
specimen, corresponds in size and position with _Dinoceras laticeps_.
The only difference between the two is a very slight one: in _D._
the curve of the posterior margin of the process is convex; in
_Uintatherium_ it is concave; the angle which the process makes with
the jaw is also greater.
_Cranial Measurements._
M.
Length of bony palate ·227
Length of head along the top ·743
Length of nasals ·398
Breadth at nasal tuberosities ·123
Distance between median projections ·385
Breadth of head posterior to median projections ·189
Breadth of head before posterior projections ·228
Breadth of head behind posterior projections ·312
Distance between extremities of posterior projections ·462
Length of nasals to ridge between median projections ·234
Length from ridge between median to ridge between
posterior projections ·374
Length of zygomatic arch (straight) ·285
Length from angle of nares to end of nasals ·162
Length from angle of nares to end of premaxillaries ·114
Width between tips of premaxillaries ·053
Circumference of median projection at top ·203
Circumference of posterior projection at top ·329
Height of median projections from ridge between them ·174
Height of posterior projections from ridge between them ·239
Length of nasals anterior to nasal tuberosities ·0415
_Teeth._--These are peculiar for their small size compared with the
bulk of the animal; for their slender fangs, and for the distance
through which these are exposed.
_Upper Jaw._--Formula: I. 0/0, C. 1/1, Pm. 3/3, M. 3/3.
_Canines._--The sockets of these teeth have been already described:
the fangs are very long, somewhat longer than the crown, and the
teeth apparently grew from permanent pulps. The crown is long,
compressed and recurved; the posterior margin is sharp, and exhibits
some indications of a slight serration.
_Premolars._--The first premolar is not preserved in our specimen.
The second and third are subequal, and of about the same
conformation. They are implanted by three fangs, one internal and
two external. The crown is subcircular at the base. The basal
ridge is large, and completely surrounds the crown; above this the
crown becomes somewhat trihedral: and is composed of two pyramidal
lobes, which meet internally and externally, and are divided by a
valley. The summits of the lobes form transverse grinding ridges;
the anterior one is the lower, and is crescent-shaped, while the
posterior is straight; the anterior ridges throughout the series are
much the most worn. The basal ridge is not indented on the outer side
at the opening of the valley as in _Dinoceras_.
_Molars._--The true molars increase in size regularly backwards. The
first molar is larger than the last premolar; it is worn down nearly
to the basal ridge, but shows a small internal accessory tubercle on
the back part of the posterior lobe. The extremities of the lobes
rise into points, and their summits are transversely concave. The
number and arrangement of the fangs in the first and second molars
is the same as that of the premolars; in the last molar there are
but two, which are long and wide, and extend the whole breadth of
the crown. This tooth is by far the largest of the molar series; it
is ovoidal in shape, with the apex at the outer point of the forward
lobe; it is proportionally broader than in _Uintatherium robustum_.
The basal ridge is strong, and extends around the entire tooth, with
some irregularities of outline at the sides. This tooth, like the
others, consists of two pyramidal lobes separated by a valley, which
in this case is wide and deep. The summit of the anterior lobe is the
longer, and extends obliquely across the crown, while the posterior
is nearly straight. The free ends and junction of the lobes are
prolonged into points, which give a tripodal character to the crown.
The outer point of the anterior lobe is the longest of the three, but
the difference is not nearly so marked as in _U. robustum_; the other
two are of about the same height; but the external is spinous in
character, while the internal is stout and obtuse. The anterior slope
of each lobe is steep, while the posterior is long and gentle. As in
_U. robustum_, there is a small rounded tubercle on the inner side
of the posterior basal ridge; but there is no tubercle occupying the
entrance of the triangular valley between the lobes. The enamel of
all the molars is smooth.
_Teeth Measurements._
M.
Length of molar series ·148
Length of premolar series ·062
Length of true molar series ·089
Fore-and-aft diameter of second premolar ·022
Transverse diameter of second premolar ·023
Fore-and-aft diameter of third premolar ·022
Transverse diameter of third premolar ·023
Fore-and-aft diameter of first molar ·023
Transverse diameter of first molar ·026
Fore-and-aft diameter of second molar ·028
Transverse diameter of second molar ·031
Fore-and-aft diameter of third molar ·039
Transverse diameter of third molar ·044
Distance between last molars ·058
Distance between first premolars ·049
Distance between first molars ·074
Fore-and-aft diameter of root of canine ·060
Transverse diameter of root of canine ·039
Length of diastema ·072
Distance between canine alveoli ·080
_Lower Jaw._--Dr. Leidy has very kindly sent us some of the lower
molars of an undescribed _Uintatherium_, which may belong to this
species. They consist of the anterior lobe of the last molar, and
second and third premolars entire. They all have nearly the same
conformation, consisting of three acute pyramidal lobes, of which
the anterior is very much the highest and broadest; the median
lobe is partly separated from the anterior by a valley which opens
outwards, while the valley between the posterior and median lobes
passes completely across the tooth. The highest point of the crown
is the inner end of the anterior lobe; but the difference between
this and the outer end, very great in the molars, becomes slight in
the premolars. The inner end has an accessory tubercle just at the
lip of the anterior lobe, and there is another on the anterior basal
ridge. This latter feature would seem to distinguish it from _U.
robustum_.
The basal ridge is distinct in front and behind, indistinct on the
external side, and entirely absent from the internal.
_Measurements._
(TEETH, LOWER JAW.)
M.
Transverse diameter of last molar ·026
Height of highest point above cingulum of last molar ·023
Fore-and-aft diameter of second molar ·0285
Transverse diameter of second molar ·023
Height of second molar ·0215
Length of fourth premolar ·021
Width of fourth premolar ·015
Height of fourth premolar ·020
Length of third premolar ·020
Width of third premolar ·015
Height of third premolar ·014
_Vertebræ._
_Cervical region_ (Plate VI., Fig. 1).--(Only one preserved, probably
fifth or sixth.)
The centrum is short, compared with the dorsals, but is much longer
than the cervical centra of the _Proboscidea_; it is broad and
depressed, oval in form, and slightly opisthocœlous. The zygapophyses
are developed upon tuberous projections of the pedicles; they are
large, flat, and in the same plane with each other. The diapophyses
are very slender and short, and but slightly heavier than the
parapophyses, with which they unite, enclosing a large vertebraterial
canal. At the anterior margin of the parapophysis, a small pointed
process projects downward.
The pedicles are low and very heavy, bounding a narrow neural canal.
The epiphyses are not so completely ossified as they are in the
dorsal region.
_Dorso-lumbar region_ (Plate VI., Figs. 2, 3, 4, 5),--(Description
based upon nine dorsals and two lumbar vertebræ.)
The centra are large, subtriangular, and slightly compressed; they
are opisthocœlous, but less so than in the _Proboscidea_. They
increase in size slowly but regularly from before backwards. In the
middle dorsal region they are excessively expanded laterally for the
posterior-costal attachments; but become less broad and higher as
they recede in the series. In the middle of the series the centra are
marked by a prominent hypophysial keel.
In the anterior dorsals the costal surfaces are developed almost
entirely upon the pedicles, and are two in number. These are very
large in about the sixth and seventh, and meet. They decrease in size
as they recede. In the middle region the posterior costal surfaces
are small, lozenge-shaped facets, and are developed upon thin lateral
projections of the centra.
The centrum of the last dorsal is heavy, resembling the centra of
the lumbar, from which it is distinguished by a single pair of small
costal surfaces, developed, half on the pedicles and half on the
centrum.
The neural spines are markedly smaller than those of the
_Proboscidea_ and _Rhinoceros_; in the anterior part of the dorsal
region the spines have the same angle as the corresponding ones in
_Mastodon_. The spines of the twelfth and thirteenth (approximately)
are much expanded at the ends and bifid; in the last dorsals they
are wide, straight, and very thin; in the lumbar region they are
short, stout, tuberous, and stand almost at right angles to the axis
of the vertebræ. The laminæ in the anterior part of the series are
long and thin, decreasing in length but increasing in thickness from
before backwards. The zygapophyses in the fore part of the dorsals
are mere flat facets on the laminæ; they increase in size and become
characteristic in the posterior part of the dorsal region. The
pre-zygapophyses of the last lumbar vertebra are very large, deeply
concave, and parallel with the axis of the column. The metapophyses
appear in the middle of the series, and regularly increase in size
to the last lumbar. From their appearance the pre-zygapophyses are
developed upon them.
The transverse processes present the most unique feature of the
vertebral column. In the anterior region they are long, wide, and
rugose, and in the same plane with the laminæ; they send directly
out wide, downward-curving projections. In the middle dorsal region
the transverse processes lose these thin projections, and become
heavy and subtrihedral, with a smooth facet on their lower face for
articulation with the tubercle of the rib; their upper face is here a
little twisted from the plane of the laminæ. In the posterior dorsal
region the transverse processes lose the facet for the articulation
with the tubercle of the rib, and become short and very thin,
pointing slightly backwards.
The lumbar transverse differ from those of the last dorsal in having
a median transverse ridge on their posterior face, and are directed
more vertically out.
The pedicles throughout most of the dorsal series are short, heavy,
and deeply notched behind. In the posterior dorsal region they become
longer and more slender, resembling almost exactly the pedicles of
the lumbar region.
_Sacral region._--The sacrum is composed of four vertebræ, three
true and one pseudo-sacral. The centra are extremely depressed, and
rapidly decrease in width and thickness from before backwards. The
first is shorter than the last lumbar, but much longer than the other
sacrals, which are subequal.
The face of the first is elliptical, and is nearly three times
the diameter of the fourth, longitudinally. The metapophyses are
exceedingly large and tuberous on the first; with wide, deeply
concave pre-zygapophyses developed upon them; in the other three the
metapophyses are rudimentary.
The transverse processes are long and wide in the first three; widest
in the first but thickest in the second; long and thin in the fourth.
The pleuropophysial segments of the true sacrals are very heavy.
The foramina enclosed by the transverse processes are large; and
have, on the internal side, their long diameter obliquely transverse
to the axis of the sacrum.
The inferior faces of the centra are slightly concave in the first
three. The first and fourth have slight hypophysial keels.
The neural canal is very wide and depressed in the first, but
decreases rapidly backwards, becoming extremely small in the last.
_Caudal region_ (Plate VI., Fig. 6).--(Description based upon the
first four.)
The centra of the caudal vertebræ are rather long, narrow, and
greatly depressed in the middle; they decrease in size gradually
backward. The pedicles and laminæ are short and thin, enclosing a
small neural canal. The neural spines point directly back, being
almost parallel with the axis of the centrum. They are slender and
tuberous at the extremity. The transverse processes are very long,
wide, and thin, thickened somewhat at the ends, and project directly
out; they decrease in size backwards. From the persistence of the
neural canal, and from its comparative size, it would seem as if the
tail was considerably larger than that of the elephant.
_Measurements of Vertebræ._
_Cervical region_ (Plate VI., Fig. 11).
M.
Diameter of cervical (vertical) ·079
Diameter of cervical (transverse) ·111
Diameter of cervical (fore-and-aft) ·051
Extreme length of prolongation of pedicles for
zygapophyses ·089
Long diameter of vertebraterial canal ·040
Width of pedicles ·035
_Dorsal region_ (Plate VI., Figs. 2 and 3).
M.
In anterior region: Diameter of centrum (fore-and-aft) ·075
Diameter of centrum (vertical) ·062
Diameter of centrum (transverse) ·142
In posterior region (Plate VI., Fig. 3).: Diameter
of last dorsal (vertical) ·087
Diameter of last dorsal (transverse) ·110
Average width throughout the series of neural canal ·097
Width of transverse process (anterior dorsal)
(Fig. 2, Plate VI.) ·075
Length of lamina from prezygs. to post-prezygs.
(Fig. 2, Plate VI.) ·12
Length of transverse process (middle dorsal).
(Fig. 3, Plate VI.) ·055
Vertical length of anterior dorsal from tip of spine
to hypapophysial keel ·183
Width between inner margins of metapophyses
(last dorsal) ·172
_Lumbar region_--Last lumbar (Plate VI., Figs. 4 and 5).
M.
Diameter of centrum (fore-and-aft) ·095
Diameter of posterior face (transverse) ·111
Diameter of posterior face (vertical) ·078
Extreme width between transverse processes ·214
Width between pre-zygapophyses ·110
Length of neural spine from lamina ·060
Vertical length from tip of spine to lower side of
centrum ·194
_Sacral region._
M.
Length of sacral series ·264
Transverse extent of sacral series ·298
Diameter of first vertebra at free end (transverse) ·109
Diameter of first vertebra at free end (vertical) ·072
Diameter of first vertebra at free end (tore and aft) ·070
Diameter of last vertebra at free end (transverse) ·053
Diameter of last vertebra at free end (vertical) ·031
Diameter of neural canal at first vertebra
(transverse) ·100
Diameter of neural canal at last vertebra (vertical) ·018
Long diameter of first transverse foramen
(internal side) ·076
_Caudal region_ (Fig. 6, Plate VI.).
M.
Length of first four ·252
Diameter of centrum, first (fore-and-aft) ·061
Diameter of neural canal of first (transverse) ·035
Extent of transverse process in first ·085
Extent of transverse process in fourth ·046
Fore-and-aft width of transverse process of first
in the middle ·048
_Ribs._--Description based upon two perfect ones, and parts of four
more.
The ribs, as in _Dinoceras_, "resemble very much those of the
Mastodon." The capitulum has two convex facets, separated by a
narrow groove. The sternal end in one is very much expanded, but
less so in the other. The tubercle is small, and is situated upon
the prolongation of the lamelliform process for the intercostal
muscles. The angle is much sharper than in the corresponding ribs of
_Mastodon_.
_Measurements of Ribs._
M.
Length of rib without curvature ·571
Length of rib with curvature ·739
Width of rib just below head ·049
Width at muscular attachment ·063
Vertical diameter of larger facet of capitulum ·039
_Scapula_ (Plate VIII., Fig. 1).--The scapula is subtriangular,
with the pre-scapular border as base, and the apex half way up the
postscapular.
On the external side the pre-scapular fossa is concave
antero-posteriorly, and plane in the direction of its length; it is
very thin in the middle, but becomes heavier at the lateral border.
The postscapular fossa is larger and less concave; both fossæ, as
they approach the upper border, gain greatly in thickness.
The spine rises from the supra-scapular border, and extends to
within an inch from the glenoid cavity. It is decidedly antroverted;
thickest and highest near glenoid cavity; thinnest and lowest in the
middle, expanding again at its upper extremity; its acromio-scapular
notch is long and shallow. The acromion is rudimentary.
The coracoid process is a low, rugose tuberosity; the coraco-scapular
notch is short and low.
The internal surface of the scapula has a large, smooth median ridge,
extending the whole length of the bone, separating it into slightly
concave fossæ. About two thirds up, the median ridge sends obliquely
up two branches, forming a V, superimposed upon the main ridge; but
these disappear before they reach the upper extremity. The whole
inner surface is curved outward, presenting a concave appearance
throughout.
The glenoid cavity is deep, ovoid in form, with its greatest diameter
fore-and-aft, and its smaller end behind.
The resemblance between the scapula of _Uintatherium_ and that of the
_Proboscidea_ is more closely marked than in any other corresponding
bones. The chief points of similarity are: first, the subtriangular
shape; second, the same relative proportions between the fossæ;
third, the antroversion of the spine; fourth, the glenoid cavity
looking directly down. The marked points of difference may be summed
up as, first, in the dissimilar proportion of the glenoid cavity;
second, the great thickening of the spine at its upper and lower
extremities; third, in the high, shallow acromio-scapular notch;
fourth, in the longitudinal concavity of the internal surface.
_Measurements._
M.
Extreme length of scapula ·42
Extreme length of spine ·31
Extreme thickness of spine at upper margin ·098
Extreme height of spine ·109
Basal width of proximal end of spine ·032
Basal width of distal end of spine ·030
Basal width of middle part of spine ·011
Length of glenoid cavity ·149
Width of glenoid cavity ·096
_The Humerus_ (Plate VII., Fig. 1).--The humerus is short, but
excessively stout, twisted slightly on its axis; it decreases
gradually in size downward, with the smallest diameter about two
inches below the end of the deltoid ridge. The head is large,
hemispherical, and sessile, projecting very slightly out of the
axis of its shaft. The great tuberosity is heavy, but not high, and
is separated from the low lesser tuberosity by a shallow bicipital
groove.
The trochleæ are very nearly equal in size, directed obliquely to
the axis of the shaft, and are separated by a narrow groove, which
runs from the supra-trochlear fossa down and in, then back and up to
the anconeal fossa. The condylar tuberosities are large and rugose;
the external is the greater, and is directed antero-posteriorly. The
deltoid ridge is long and heavy, and extends nearly two thirds down
the shaft, branching out into two forks near its end. The supinator
ridge is short and rudimentary, differing in this respect entirely
from the great development found on the humerus of the _Proboscidea_.
The supra-condylar fossa is small, subcircular in form, and very
deep, it has the peculiarity of being placed above the external
condyle alone. The anconeal fossa is median in position and quite
deep.
_Measurements of Humerus._
M.
Length ·63
Smallest circumference of shaft just below deltoid
ridge ·288
Greatest proximal circumference below greater
tuberosities ·45
Width of trochlea on anterior side ·154
Length of anconeal fossa ·071
Width of anconeal fossa ·062
Width of distal end at condylar tuberosities ·23
Length of deltoid ridge ·22
Length of groove running from supra-trochlear to
anconeal fossa ·272
_The Ulna_ (Plate VII.. Fig. 2).--The ulna is long, heavy at both
ends, with a slender trihedral shaft that curves forward, and
decreases in size as it approaches the distal end. The proximal end
has its articular face for the humerus divided into three facets,
the vertical being long and extremely convex; the horizontal has the
pre-axial face the longer. The olecranon is very massive and rugose,
sending up on its external side a high, pointed projection; while
on the internal side, the olecranon becomes compressed and projects
inward; these tuberosities are separated by a wide, shallow groove
for the tendon. The distal articular face is large, single, and is
concave antero-posteriorly, and convex laterally. The styloid process
is very heavy.
_Measurements of Ulna._
M.
Length of sigmoid notch ·089
Width of sigmoid notch (horizontal face) ·049
Diameter of proximal end below articular face
(fore-and-aft) ·076
Diameter of proximal end below articular face
(transverse) ·059
Diameter of distal articular face (fore-and-aft) ·061
Diameter of distal articular face (transverse) ·051
Length of olecranon ·112
_Pelvis._--The _ilia_ are greatly expanded laterally, with the iliac
surface concave and the gluteal surface nearly flat; thin in the
middle, they increase in thickness near the borders. The crests curve
regularly, and project above and beyond the sacrum, but do not bend
over the acetabula. The acetabular borders are only slightly concave;
the prominence for the attachment of the rectus muscle (extensor) is
low and V-shaped. The direct internal surfaces of the ilia, comprised
between the pubic and ischiatic borders, become deeply concave below
the ischiatic portion of the acetabulum. The sacral surfaces are wide
and triangular in shape; above they project beyond the sacral spines.
The ilio-lumbar angle is about 110°. The ischium is, short; a section
of it, as it leaves the acetabulum, is subtriangular; but immediately
it becomes flattened fore-and-aft throughout its plane of 90° to the
axis of ilium; then verging toward the pubic symphysis it becomes
small. The tuberosity of the ischium is small and directed up.
The pubis, as it leaves the acetabulum, is sub-cylindrical, after
this it is flattened in the same plane with the ischium. The bone
as a whole is short, thin, and slightly curved on its own axis; its
smallest part makes up the pubic symphysis, which is short. The
thyroid foramen is a large oval, with its long diameter parallel to
the axis of the ischium.
The acetabulum is large, subcircular, and deep, with prominent
borders; especially the iliac, which is produced on its external
extremity into a point; the ischiatic is deeply notched. From the
wide ligamentous pit in the centre there runs a deep groove part way
down the antero-external side of the ischium.
The anterior opening of the pelvis is a wide oval, with its longest
diameter transverse.
_Measurements of Pelvis._
M.
Transverse diameter of pelvis, including sacrum 1·171
Long diameter of ilium (from lower margin of the
crest to sacral surface) ·440
Short diameter of ilium (from acetabulum to upper
margin of crest) ·393
Length of acetabular border ·125
Length of ischium ·220
Width of ischium at tuberosity ·124
Length of pubis ·196
Greatest width of pubis ·061
Smallest width of pubis ·027
Long diameter of acetabulum ·139
Short diameter of acetabulum ·118
Long diameter of thyroid foramen ·094
_The Femur_ (Plate VIII., Fig. 4).---The femur is short, with a
small oval head, strongly compressed fore-and-aft. It is less out
of the axis of shaft than in _Proboscidea_, and has no pit for the
ligamentum teres. The shaft is straight and simple, much compressed
transversely at the proximal extremity, becoming sub-cylindrical
below.
The great trochanter is heavy, rugose, and strongly recurved; it is
separated from the shaft by a wide and deep digital fossa. The second
trochanter is a mere rudimental tuberosity. The condyles are nearly
of an equal size, very convex, and are divided by a deep popliteal
groove.
The condylar tuberosities are low, the internal sends obliquely a
ridge three inches long, up and across the axis of the shaft at an
angle of 45°, that forms the upper boundary of the popliteal space.
The front part of the trochlear faces for the patella are gone in our
specimen.
_Measurements of Femur._
M.
Greatest distal diameter across condyles ·178
Length of condyles ·079
Transverse diameter of shaft six inches above
distal end ·121
_The Tibia_ (Plate VIII., Fig. 2).--The tibia is short, straight, and
simple, slender in the middle, but much expanded at the extremities.
The proximal end is especially massive, with deeply concave articular
faces; the internal cotylus is the larger, and has its greatest
diameter fore-and-aft, directly at right angles to the greatest
diameter of the external.
The cotyli are separated by a smooth ridge, that is highest at its
posterior termination. The tuberosity is high and massive, with a
wide depression on its top for the reception of the ligament of the
patella; the sides are deeply pitted by venous foramina. A section of
the shaft at the lower part of the tuberosity would be subtriangular;
while below it becomes more cylindrical, as it becomes smaller,
reaching its shortest diameter about three fifths down the shaft.
Below this it expands and forms the large subcircular distal end.
The articular face is concave, with a slight, smooth ridge running
fore-and-aft on its internal side. The malleolus is broad and low.
The _fibula_ is distinct, but very slender; its proximal end has a
small circular face, which articulates with the tibia on a facet
developed on the bottom of a projection of the tuberosity; the distal
end is much flattened, but enters into the ankle-joint.
_Measurements of the Tibia._
M.
Transverse diameter of proximal articulation ·158
Longitudinal diameter of proximal articulation ·123
Smallest circumference of shaft ·16
Greatest distal circumference above the articular face ·308
Diameter of distal articulation longitudinally ·082
Diameter of distal articulation transversely ·130
Width of tuberosity below pit for ligament of the
patella ·075