16 



University of California Publications. 



[Geology 



PLEISTOGYPS EEX, n. gen. and sp. 



Type specimen No. 12599, Univ. Calif. Col. Vert. Palae. 

 Tarso-metatarsus. 



Size very large. Intercotylar tuberosity very inconspicuous. 

 Head almost symmetrical upon the shaft. Foot narrow and 

 rotated inward; inner toe much in rear of outer and reaching 

 almost the same level as middle toe. Groove of middle trochlea 

 not in sagittal plane. 



This last well defined group in the series of tarsi assembled 

 consists of five specimens representing at least four, and probably 

 five, different individuals. The superficial appearance is most 

 nearly like Sarcorhamphus clarki but closer scrutiny renders any 

 confusion impossible. S. clarki stands as the smallest of the 

 entire series and the present species is at the opposite extreme 

 in size. The relatively narrow foot, the inconspicuous inter- 

 cotylar tuberosity and the less flattened shaft and head, serve to 

 differentiate the form at once from Sarcorhamphus and Gym- 

 nogyps. The greater robustness, the more symmetrical head and 

 the narrow, intoed foot distinguish it readily from Cathartomis 

 gracilis. 



Front aspect. — The head region is excavated much as in C. gracilis 

 but the cavity is smaller and more nearly circular. To the outer side of 

 the cavity just below the margin of the outer articular facet, there 

 appears a large round headed tubercle. To the inner side of the cavity 

 and at a slightly lower level than the upper limit of the cavity there 

 appears a small, sharp papilla. The intercotylar tuberosity, as above 

 mentioned, is low and mound-shaped. The attachment of the tibialis 

 anticus takes the form of two papillae, the outer elongate one placed 

 slightly above the inner, more nearly circular one. Below these papillae 

 the shaft is moderately excavated, the lateral margins appearing as 

 smoothly rounded ridges. The outer ridge becomes more sharply angled 

 as it nears the middle portion of the shaft, and despite the fact that 

 the anterior furrow here becomes practically obsolete passes thence as 

 a definite ridge almost straight to the outer border of the distal 

 foramen. The narrowest place in the shaft is at just about the middle 

 point. From this point, the enlargement in either direction is quite 

 gradual. The curvature on the inner side at the foot region is slightly 

 greater than on the outer side. In the head region, the curvature is 

 almost equal on both sides. The trochleae reach more nearly the same 

 level than in any of the species hitherto discussed. The inner trochlea, 

 in fact, descends almost to the same level as the middle one. 



