EDENTATA OF THE SANTA CRUZ BEDS. 133 



The entocuneiform also is more armadillo-like than that of the Pam- 

 pean genera ; it is relatively large, especially in the dorso-plantar and 

 proximo-distal diameters and distally it not only articulates with the first 

 metatarsal, but also quite extensively with the second. 



The mesocuneiform is very small and is proportionately more reduced 

 than in the Pampean types, except Sclerocalyptus ; its only considerable 

 diameter is the dorso-plantar and the exposed faces are nearly square. 



The ectocuneiform is very large on the dorsal side, contracting to a 

 blunt edge on the plantar ; the bone is placed obliquely in the tarsus and 

 distally articulates with the second and third metatarsals. In the Pam- 

 pean genera the ectocuneiform is relatively very much broader and may 

 extend over upon the head of metatarsal IV. 



The cuboid is short, especially upon the fibular side, which is owing to 

 the obliquity of the calcaneal facet ; though short, the cuboid is broad and 

 thick and has a massive process from the plantar face. In its proportions 

 this cuboid is intermediate between that of Sclerocalyptus and that of Glyp- 

 todon; in the former it is longer and narrower, while in the latter it is far 

 wider and shorter. 



The metatarsus consists of five members, all of which are short and 

 heavy, though less so than in the Pampean genera. Metatarsal I is much 

 the shortest of the series and its breadth nearly equals its length ; the 

 distal trochlea is reflected far over upon the plantar face and is grooved, 

 but has no keel. 



Metatarsal II is almost twice as long as I, but very short and heavy ; 

 its broad proximal end articulates with all three of the cuneiforms ; the 

 shaft is short, broad and very thick, somewhat contracted near the prox- 

 imal end and widening distally ; the trochlea extends far over upon both 

 plantar and dorsal faces, and has a slight median groove and a distinct 

 plantar carina. 



Metatarsal III is somewhat longer and considerably stouter than II ; it 

 has a broader head, a shaft of more uniform width, and a similar trochlea. 



Metatarsal IV is of nearly the same length as II, but has a more 

 rounded shaft and shorter trochlea. 



Metatarsal V is extremely short and of only moderate thickness ; its 

 trochlea is slightly convex. 



The phalanges are likewise very short and broad, especially those of the 

 median three digits (II, III, IV) which are much larger in every dimen- 



