608 ZOOLOGY sect. 



surface. The fibula does not articulate with either the astragalus 

 or the calcaneunii. 



Another extinct primitive sub-order of the TJngulata is the 

 Am'bly2)oda, the members of which have been found, like the 

 Condylarthra, in the Eocene of North America and of Europe. 

 These resemble the Condylarthra and Hyracoidea in the scaphoid 

 being opposite the trapezoid ; both magnum and unciform articulate 

 with the lunar. The fibula articulates with the calcaneum ; the 

 cuboid articulates with both the astragalus and the calcaneum ; 

 The feet are short, pentadactyle, and plantigrade. Canines are 

 present in both upper and lower jaw ; the pre-molars and molars 

 are short and lophodont in type. Dinoceras and Tinoceras are 

 characterised by the process of remarkable bony prominences on 

 the upper surface of the skull. In the Tertiary deposits of 

 Patagonia and Bolivia have been found the remains of another 

 group of extinct Ungulates of low organisation — the Litoptcrna, 

 These had the distal segments of the limbs elongated and 

 constructed on the perissodactyle type, the number of the digits 

 varying from five to one, the third being always the largest. The 

 carpal and tarsal bones do not interlock as in the existing 

 TJngulata vera. There is no foramen above the inner condyle and 

 clavicles are absent. A third trochanter is present. The brain- 

 case is very much smaller than in the existing Ungulata vera. 

 The dentition is complete or nearly so ; the pre-molars and molars 

 short and provided with roots. 



The Ancylopoda are anothei- group of primitive extinct Ungulates. 

 The remains of some of these have only been found in the Pata- 

 gonian Tertiary deposits, but others had a wide range both in the 

 Old and New Worlds. They all differ from other groups of 

 Ungulates in the form of the limbs : the weight of the body 

 appears to have been borne on the outer edge of the manus and 

 pes, and the digits were evidently provided, not with true hoofs, 

 but with pointed claws. The teeth resemble those of the 

 Perissodactyla. 



The Typotheria and Toxodontia are two groups of extinct 

 Ungulata the representatives of which have only so far been found 

 in the South American Tertiary formations. The former differ 

 from ordinary Ungulates in the possession of a clavicle and the 

 presence of a foramen above the inner condyle of the humerus. 

 The ulna and fibula are complete, and there are either four or five 

 fully formed digits in each foot. The Toxodontia approach nearer 

 the normal Ungulate type, the clavicle and the foramen over the 

 inner condyle being both absent. They have a massive skull and 

 short, stout limbs, each with three digits. 



The true Carnivora of the Tertiary period are, as compared with 

 those of the present time, remarkable for the absence of the well- 

 marked distinction into groups such as are now to be recognised ; 



