. Bulletin - American Museum of Natural History. Natural history; Science. protoloph '- mctaloph Fig. 9. Hyrachyus agrarius. Premolar series of left side. Diagram exhibiting the three regular stages of progression from pjj to P- -t, in contrast with that of the Lophiodonts. parastyle crjs/a Lower Premolars.—These teeth exhibit a similar progression, the last being decidedly the most complex ; they show a high, obliquely placed metalophid and a low, basin-shaped talonid, which exhibits no trace of the hypolophid or posterior crest. Molars.—The molars are incipiently but not fully rhinocero- tin
. Bulletin - American Museum of Natural History. Natural history; Science. protoloph '- mctaloph Fig. 9. Hyrachyus agrarius. Premolar series of left side. Diagram exhibiting the three regular stages of progression from pjj to P- -t, in contrast with that of the Lophiodonts. parastyle crjs/a Lower Premolars.—These teeth exhibit a similar progression, the last being decidedly the most complex ; they show a high, obliquely placed metalophid and a low, basin-shaped talonid, which exhibits no trace of the hypolophid or posterior crest. Molars.—The molars are incipiently but not fully rhinocero- tine, because the elongation of the paracone, and consequent asymmetry of the external cusps, which is the distinctive feature of the rhinoceros molar, has not progressed very far. The second molar is the largest and most pro- gressive tooth of the series ; it displays a prominent parastyle, traces of a cingulum at the base of the metacone, a prominent anterior cingulum, a feeble posterior cingu- lum, and an incomplete internal cingulum. It exhibits a strong pro- toloph, a more slender metaloph and Fig. 10. Hyrackusagrarius. Dia- a delicate crista, but there is no gram of second upper molar of the left r , r side. trace of an anticrochet or of a. 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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