2 I 2 COPE ON THE TYPOTHERIA CHAP. 



trochanter, and the unguiculate claws have akeady been referred 

 to. As to the latter, which are short, it is not the end phalanx 

 but the first which is retracted; thus C]i(diciit]irriuvi differs 

 markedly from both Carnivorous and Edentate types ; for in the 

 former it is the last phalanx which is retracted, while in the 

 Edentates the same phalanx is flexed downwards. The limbs of 

 C/udicothermm are nearly of the same size, and the animal 

 seems to have been stout and quadrupedal.^ 



Macrothcrimn, like the last genus, seems to have been 

 common to both New and Old Worlds. It is to be distinguished 

 by a number of characters. It is supposed to have been " semi- 

 arboreal and fossorial " ; the fore-limbs are much longer than 

 the hind, the relative proportions of the radius and tibia being 

 70 to 29. The ulna was distinct from the radius, whereas in 

 Chalicotherium the two are coalesced, or nearly so. Young 

 specimens appear to possess a full set of incisors ; whether this 

 is the case or not with C/ialir.otherium is not known.^ 



Homalodontotheriumi is sometimes placed in the group. 



Sub-Order 4. TYPOTHEEIA. 



It is a little diflicult to be confident that the Typotheria are 

 rightly referred to the Ungulata, since they contradict two im- 

 portant Ungulate rules. They have clavicles, which are elsewhere 

 missing, and the thumb looks as if it were opposable.^ An 

 Ungulate is essentially a running animal, and has no need of a 

 grasping finger. Still Typotheria are placed by most within the 

 Ungulate series, though their undoubted likenesses to other 

 groups, especially to the Eodentia, are admitted, and indeed 

 emphasised. Cope places them definitely with the Toxodonts. 



The Typotheria are an extinct group of smallish beasts, 

 confined, like the Toxodontia, to South America, a region which 

 during the Tertiary period, and into the Pleistocene, abounded 

 with strange and varied types of Ungulate animals. 



The earlier forms of Typotheria may be exemplified by some 



' See Osborn, American Naturalist, February 189.3, p. 118. 



^ It is not absolutely clear wliether both or only one genua ranged into 

 America. Different opinions have been expressed. 



' It must be remembered, however, that there is a suggestion of a prehensile 

 character in the hand of Phenacodus (see p. 203). 



