EDENTATA OF THE SANTA CRUZ BEDS. 313 



It consists of the mandible, with dentition complete ; four cervical, sixteen 

 thoracic, one lumbar and two caudal vertebrae; the right scapula and 

 humerus, left ulna and part of manus ; the right ilium and femur ; both 

 tibiae and the greater part of the pes. The skeleton is much more distinct 

 from that of the other genera than would have been expected from the 

 teeth and skull only. 



The dentition is not especially characteristic; T is very slender, of 

 longitudinally elliptical section, with major axis somewhat oblique to the 

 line of the other teeth, while the crown is erect and quite high. Although 

 the alveoli of T and ^ are separated by a very thin lamina of bone, the 

 space between the teeth themselves is greater than between any succeed- 

 ing pair, because neither tooth completely fills its socket ; ^ is large, much 

 compressed antero-posteriorly and transversely oval, with major axis' 

 oblique to the line of the dental series ; is similar, but slightly larger 

 and less oblique; T is subcylindrical, especially in the type, while in 9,240 

 it is more of an oblique oval. 



MEASUREMENTS. 



Type. No. 9,24.0. 



Lower dentition, length 03 1 .03 1 



" j_ 3 022 .023 



T , length (t. e., antero-posterior diameter) .005 



" width (i. e., transverse diameter) .004 



2 , length 005 5 .006 



" width oio .008 



-g, length 007 .0065 



"' width 0095 .0085 



T , length 0075 .007 



" width 0095 .009 



The mandible differs in several respects from that of P. cristatus, espe- 

 cially in the much greater sinuosity of the ventral border, being more 

 convex under the horizontal ramus and much more concave under the 

 ascending ramus ; the sudden thickening of the former at its posterior 

 end projects more externally in P. cristatus and more internally in the 

 present species ; the angular process is very long and prominent, extend- 

 ing well behind the condyle, and is broader dorso-ventrally than in P. 

 cristatus; its ventral border is but slightly inflected, much less than in 

 the large contemporary genera. The condyle is placed upon a shorter 

 neck than in the species last named and projects more upward, less back- 



