246 



SUBUNGULATA 



ORDER IX 



Radius short and fused with ulna. Olecranon high. Ilium joined to the 

 sacrum for a considerable distance. Femur with only first trochanter, but 

 with high head. This bone and the tibia are placed in the same vertical 

 line one over the other. The fibula is fused with the tibia above and 

 below. The astragalus is flattened and has a smooth tibial facet directly 

 adjoining those for the navicular and calcaneum. The navicular is entirely 

 underneath the astragalus, which possibly gives rise to the vertical arrange- 

 ment of the toes. 



The teeth as well as the bones of the extremities are similar to those 

 of the Prohoscidea, especially Binotherium, and for this reason Ameghino 

 traces the origin of the Prohoscidea back to Pyrotheriwn. In dental structure 



there is also a great 

 likeness to Dip'otodon. 

 There can, however, be 

 no relationship between 

 this form and either the 

 Marsupials or the Pro- 

 boscideans. The origin 

 of the Pyrotheria is at 

 present wholly un- 

 known. 



Pyrotherinm Ameg- 



,. 2.? 0.3.3. ,^. 



hino. - — ^ ^ ^ (-tis;. 

 1. 0.2.3. ^ ^ 



331). The ridges of 



the quadrangular molars 



Pjq_ 33]^ are at right angles to 



Pyrotherium romeroi Amegluuo. Lower Miocene, Patagonia. ^, Upper the tOOthrOW, posteriorly 

 cheek teeth, grinding surface, 1/4. B, Lower jaw, left lateral aspect, r^r^ntrav /->« flin 1/-vnrnT. 



i/i2- (After Gaudry.)- convex on^ cne lower, 



and anteriorly convex 

 on the upper molars. Lower Miocene of Chubut, Patagonia. P. romeroi 

 Ameghino. 



Propyrotherium Ameghino. Smaller than the preceding form. Oligocene ; 

 Astraponotus beds. P. saxeum Ameghino. 



Caroloziffelia Ameghino. Lower incisor with long root. Upper molars 

 rounded with two posteriorly directed ridges. Lower molars oval, with two 

 ridges almost at direct right angles to the tooth-row. M^ with third ridge. 

 About the size of a tapir. Upper Eocene ; Notostylops beds of Patagonia. 



Bicardowenia, Paulogervaisia and Archaeolophus Ameghino. Very problematic 

 remains. 



Order IX. SUBUNGULATA. 



Usually large, plantigrade or digitigrade herbivores or anir^ials adapted for 

 aquatic life, having originally a complete hrachyodont-hunodont dentition. A j^air 

 of incisors are enlarged in early forms, often developing into tusks, the remaining 

 incisors and canines reduced, entirely lacking <w gradually passing into one another. 

 The molars are practically quadritubercular, the upper ones equally as long as broad. 

 The premolars are very like the molars. Bones of carpus and tarsus slightly alternating 



