. Annals of the Carnegie Museum. Carnegie Museum; Carnegie Museum of Natural History; Natural history. 162 Annals of the Carnegie Museum. flaring to accommodate the large Py as mentioned above. Anteriorly the two rami form a rather broad square chin which terminates in- feriorly in a heavy rounded swelling. The external surface of the horizontal ramus is quite plane between P2- and the vertical rugosity for the posterior margin of the alveolo- labialis muscles, while internally the surface is convexo-concave supero-inferiorly opposite the molar region. The under border of the horizontal ramus
. Annals of the Carnegie Museum. Carnegie Museum; Carnegie Museum of Natural History; Natural history. 162 Annals of the Carnegie Museum. flaring to accommodate the large Py as mentioned above. Anteriorly the two rami form a rather broad square chin which terminates in- feriorly in a heavy rounded swelling. The external surface of the horizontal ramus is quite plane between P2- and the vertical rugosity for the posterior margin of the alveolo- labialis muscles, while internally the surface is convexo-concave supero-inferiorly opposite the molar region. The under border of the horizontal ramus forms a long antero- posterior concavity due to the heavily rounded chin, and to the de- scending angle at the back of the jaw. The mental foramina are located well down on the jaw; one opposite the anterior part of Pg- and the other opposite Fig. Side view of left lower jaw of Promerycochcerus carrikeri No. 109; 5 natural size. The depressed appearance of the vertical ramus is due entirely to the unusually small elevation of the ramus above the horizontal line of the teeth. Thus the coronoid process is a mere blunt and short peg, very little higher than the articular condyle, and strongly directed outward. At the base of the antero-internal angle of the coronoid process there is a broad rugose ai'ea for muscular attachments, which is succeeded by an equally broad though smoother area on the postero- internal angle of the same process, which terminates at the anterior border of the articular condyle. The latter is quite broad transversely, but has a small antero-posterior diameter, while internally it greatly overhangs the pterygoid fossa. The latter fossa is extremely large, quite concave, and has many rugose ridges across it for the attach- ment of the internal pterygoid muscle. There is also a prominent ridge and a rugose area for the attachment of the muscles (external pterygoid) on the neck of the articulating condyle. The dental fora- men is of medium size and is pla
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Keywords: ., booka, bookcentury1900, bookdecade1910, booksubjectnaturalhistory
