. Bulletin - American Museum of Natural History. Natural history; Science. 136 Bullettn American Museum of Natural History. [Vol. XXII, of the metastylid which, at its summit in the Httle worn teeth, is sHghtly separated from the metaconid by a shallow groove which extends but a short distance down the side of the metaconid pillar. The continuous external basal cingulum is well developed in a broad heavy band of enamel. Diameters of type tooth, Measurements, dp* Diams. of lower teeth (No. 10834)- Antero-post. 27 mm. Transv. 29 mm. 28 275 20 21. raj " 20 " Height of crown, p^, in
. Bulletin - American Museum of Natural History. Natural history; Science. 136 Bullettn American Museum of Natural History. [Vol. XXII, of the metastylid which, at its summit in the Httle worn teeth, is sHghtly separated from the metaconid by a shallow groove which extends but a short distance down the side of the metaconid pillar. The continuous external basal cingulum is well developed in a broad heavy band of enamel. Diameters of type tooth, Measurements, dp* Diams. of lower teeth (No. 10834)- Antero-post. 27 mm. Transv. 29 mm. 28 275 20 21. raj " 20 " Height of crown, p^, inside 20 mm., outside 25 mm. Hypohippus sp. indet. A single left lower molar (No. 10835 Amer. Mus. Coll.), mj or m2, from Big Spring Cafion, represents a second Upper Miocene species of Hypohippus much smaller than H. affinis. This tooth shows less progressive characters: (i) The crown is relatively shorter; (2) the metastylid is less developed, with no separating notch; (3) the basal cingulum is relatively weaker and narrower. i Jl^' ""^T-^A^"' The tooth is larger than the corresponding one in H. nipptis sp. indesc. o r b ' nauirailTz'^' No^ equiuus. It diffcrs further from that species in having formatiL°"s ^Da"^ ^ narrowcr cingulum and somewhat greater com- ^°^^- parative height of crown. The measurements are: Antero-post. diameter mm. Transv. " 23 " Height of crown inside 12 " " outside 16 " The tooth probably represents an undescribed species, but we prefer not to name a species on such an incomplete and uncharacter- istic specimen. Protohippus perditus Leidy. This species is represented by a nearly complete skull (No. 10838 Amer. Mus. Coll.), which may be regarded as a hypotype,i and a well preserved palate containing the milk molars (No. 10866), both 'See Schuchert's definition, Science, Vol. V, 1897, p.' Please note that these images are extracted from scanned page images that may have been digitally enhanced
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