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which sends a branch forwards for a considerable distance, often so 

 far as to articnlate 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 cornu" or stylo-hyal bone is attached; 

 while in the Hog-tribe this process is so com])letely 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 lamellifonii 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 Camelidae. 

 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 zj'goma 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 Camelidce. The pterygoid ridge 

 terminates in an angle, which, however, is not prolonged into a pro- 

 cess ; from this angle there is no 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 



