. Bulletin - American Museum of Natural History. Natural history; Science. -°4 Bulletin American Museum of Natural History. [Vol. VI, The younger individual (No. 521) shows all the upper pre- molars of the first series in place. The first premolar has a long ectoloph and two irregular transverse crests. The second pre- molar his two perfect transverse crests. The third premolar has two crests which are confluent internally ; it is more triangular in form and less progressive than the second premolar. The fourth premolar is on the other hand more progressive than the molars, E. B the First and
. Bulletin - American Museum of Natural History. Natural history; Science. -°4 Bulletin American Museum of Natural History. [Vol. VI, The younger individual (No. 521) shows all the upper pre- molars of the first series in place. The first premolar has a long ectoloph and two irregular transverse crests. The second pre- molar his two perfect transverse crests. The third premolar has two crests which are confluent internally ; it is more triangular in form and less progressive than the second premolar. The fourth premolar is on the other hand more progressive than the molars, E. B the First and Se >nd Series \. I tratkerium t noduin. type (No. 52S). 1!, Aceratherium. mite (No. 522). E, Aceratherium plalycepha- lum(Ho. 540) Showing by the internal view the persistence and unchanged form ol the two 1 milk teeth, D. 1 I thi evolution ol the postero-internal lobe in ilic third and fourth premolars, P. i, P. 4. Two-thirds natural size. with protoloph and metaloph, an antecrochet and a tuben le al the entrance ol the median valley. It is somewhat doubtful whether the incisors and the canine belong to the first or second serii Aceratherium occidentale {Leidy). Plati 11. C. This classic species is represented l>\ numerous specimens, including three fairl) well-preserved adult skulls (Nos. 532,535,. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original American Museum of Natural History; Allen, J. A. (Joel Asaph), 1838-1921. New York [American Museum of Natural History]
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Keywords: ., bookcentury1800, booksubjectnaturalhistory, booksubjectscience
