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which sends a branch forwards for a considerable distance, often so 
far as to articulate with the lacrymal bone. They also differ from 
the Hog-tribe in having, like the Perissodactyla, a distinct styloid pro- 
cess, emanating from the mastoid bone, partly enclosed by a portion 
of the tympanic, and with a truncated extremity, to which one of the 
angles terminating the “lesser cornw’ or stylo-hyal bone is attached ; 
while in the Hog-tribe this process is so completely pressed between 
the paroccipital process and the auditory bulla, that in most cases it 
does not seem to exist. 
It will perhaps be most convenient to assign the rank of “ family” 
to the four generally received subdivisions of this ancient order, 
although the osteological differences which they present are very 
slight ; such few as I could find in the skull I will now point out. 
In the Camels and Llamas, the articulation of the lower jaw differs 
from that of Ruminants in general, in having a distinct eminentia ar- 
ticularis, separated by a fossa not having the character of an articula- 
ting surface from the post-articular process, upon which is another 
facet ; the condyle of the jaw having likewise two articulating surfaces 
placed at right angles with each other. There is also a marked pe- 
culiarity in the auditory bulla, since the outer wall of the vaginal 
process forms a deep, thickened, vertical plate, burying the styloid 
process between it and the opposite part of the bulla. On looking at 
the casts of the skull of the Anoplotherium existing in our museums, 
I perceive, immediately under the meatus auditorius, a strong vertical 
process, apparently the outer edge of this lamelliform expansion, the 
remainder being concealed in the matrix. I fully concur in Professor 
Owen’s reasons for considering the Anoplotherium as a ruminant, and 
this indication of character, in addition to the many resemblances 
which authors have pointed out, renders it probable that this early 
representative of the Artiodactyla belonged to the family Camelide. 
The existing members of this family also most approach the Anoplo- 
therium in the form of the ascending ramus of the lower jaw, and the 
strongly-marked notch which bounds the angular process above. 
I am glad to find that I have the sanction of Professor Owen’s 
opinion in referring the Merycopotamus to the ruminant division, 
since on examining the specimens in our National Museum, I find 
that in addition to the form of the teeth, which if taken alone are not 
always to be depended on, all the essential characters of the skull are 
in accordance with that type. The masseteric ridge reaches to within 
half an inch of the orbit, and above the zygoma is a distinct indication 
of the foramen usually existing there in Ruminants. The glenoid 
surface is slightly convex anteriorly, and terminated behind by a di- 
stinct post-articular process, on to which the articulating surface is 
continued without intermission, thus indicating the animal to be ru- 
minant, but removing it from the Camelide. The pterygoid ridge 
terminates in an angle, which, however, is not prolonged into a pro- 
cess ; from this angle there is zo transverse lamina extending down to 
join the pterygoid process, and consequently no pterygoid fossa. The 
articulating surfaces of the occipital condyles seem to extend on to 
the processes anterior to them; the auditory bulla is rounded, but 
