EDENTATA OF THE SANTA CRUZ BEDS. 307 



pressed and of almost uniform diameter, except near the distal end, 

 where it is much enlarged ; the distal end is very heavy, less elongate 

 than in Hapalops, with notably smaller tibial and more nearly plane 



astragalar facet. 



MEASUREMENTS. 



Atlas, length 022 Fibula, length 114 



" dorso-ventral height 026 " thickness of proximal end 023 



Ulna, length 141 " width of shaft in middle 0065 



" " of olecranon 015 " thickness of shaft in middle . . . .0095 



" width of humeral trochlea 019 '" width of distal end 020 



" " " distal end 0125 " thickness of distal end 025 



PELECYODON Ameghino. 



(Plates LII, LIII, Figs. 2 7.) 



Pelecyodon Amegh. ; Rev. Argent, de Hist. Nat, T. I, 1891, p. 323. 

 Uranokyrtus Amegh. ; Enum. Synopt. des Mamm. Foss. de Patagonie, 



1894, p. 159. 

 Adiastemus Amegh. ; Ibid, p. 160. 



Although closely allied with Schismotherium, Pelecyodon is a well dis- 

 tinguished genus. The dentition is especially characterized by the shape 

 of the upper caniniform, which is much compressed laterally and extended 

 antero-posteriorly and is plane on the inner, convex or angulate on the 

 outer face ; in some examples this tooth is abraded only on the posterior 

 face, in others it is bevelled to a sharp point; it is inserted somewhat 

 hearer to the anterior edge of the maxillary than in the preceding genus. 

 The teeth are implanted in nearly continuous series, but with slightly 

 longer interspace between - and - than between the succeeding teeth. 

 The second upper tooth, -, is more or less cylindrical, but rather narrower 

 in front than behind ; z , -, and - are transversely oval, a the largest and * 

 much the smallest of the series. In the lower jaw f T is small, laterally 

 compressed and of elliptical or obscurely trihedral section, and is sepa- 

 rated from ? by an even shorter space than that between - and - ; ? and * 

 are transversely oval and \ is subcylindrical. 



The skull is longer and narrower than in Schismotherium, but the orbit 

 is slightly more advanced and the face is therefore somewhat shorter ; the 

 sagittal crest is well defined and the occipital crest is thin, but more or 

 less prominent, and its median dorsal portion is but slightly curved for- 



