. Bulletin of the Department of Geology. Geology. 428 University of California Publications in Geology [Vol. 7 for doubt that the two jaws represent the same species. The species represented by specimens 19840 and 19764 seems distinct from any form thus far described. In spite of its frag- mentary nature, the upper jaw specimen is selected as the type, as the characters of the superior cheek-tooth series seem more significant in discussion of the relationships. Upper Cheek-teeth.—In the specimen representing the upper jaw (fig. 3), the well-preserved, unworn, inner portion of M1 offers good op
. Bulletin of the Department of Geology. Geology. 428 University of California Publications in Geology [Vol. 7 for doubt that the two jaws represent the same species. The species represented by specimens 19840 and 19764 seems distinct from any form thus far described. In spite of its frag- mentary nature, the upper jaw specimen is selected as the type, as the characters of the superior cheek-tooth series seem more significant in discussion of the relationships. Upper Cheek-teeth.—In the specimen representing the upper jaw (fig. 3), the well-preserved, unworn, inner portion of M1 offers good opportunity for examination of certain distinctive characters of this form. In this tooth the metaloph is fully united with the ectoloph. The protoconule is distinctly separate from the protocone, it is considerably elongated and flattened,. 3 4 Fig. 3. Parahippusf ?) mourningi, n. sp. Dm', Dm4, and M1. No. 19840, X I1/;. Mohave Miocene, Barstow Syncline, Mohave Desert, California. Fig. 4. Archaeohippus ultimus (Cope). Upper molar. No. 1689, X 1%. Middle Miocene, Mascall Beds, Eastern Oregon. and its inner end slightly overlaps the protocone. The hypostyle is larger than in Hypohippus and Archaeohippus, and there is a more distinct cup-like depression behind it. There is no sug- gestion of a crochet, though several plate-like projections arise from the anterior side of the outer e^l of the metaloph. The cingulum is well developed n the posterior side, and less dis- tinctly on the anterior side between protocone and protoconule. There is no shelf of the cingulum on the inner or lingual side of the tooth. The cusps or ridges of the crown are somewhat higher than in Archaeohippus or in Hypohippus. The surface shows a degree of rugosity more pronounced than seems char- acteristic of Hypohippus or of Archaeohippus. No trace of cement is evident upon the Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability
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