Henry's Fork.
Hyrachyus agrarius, Leidy.
Pr. Ac. Nat. Sc., 1871, 229.
Henry's Fork.
Hyrachyus eximius, Leidy.
Pr. Ac. Nat. Sc., 1871, 229.
Cottonwood Creek.
Hyrachyus crassidens, sp. nov.
Established on the left and a portion of the right ramus mandibuli, containing the first molar.
The jaw presents some differences from the form common in Hyrachyus. The alveolus is more curved, especially near the ascending portion of the ramus; the jaw is narrower, and is especially contracted near the incisive alveolus. The lower margin of the ramus is but slightly curved. The ramus itself thickens regularly from before backwards, and is thickest at the last molar; beyond which it becomes thinner again. The depth of the jaw is comparatively small, and the teeth have a forward inclination; the mental foramina are not so large as in other species of Hyrachyus, and are four in number.