ANOPLOTHERE. 523 



CHAPTER XII. 



TEETH OF UNGULATA. 



The most complex and varied sj^stems of dentition are to be 

 found in the different Orders, Families and Genera of the great 

 natural group of hoofed Quadrupeds. From this group it will 

 suffice for the objects of the present Work to select certain 

 examples to elucidate the leading modifications of the systems of 

 complex teeth, and these examples will be taken from the typical 

 species of the Isodactyle(l), the Anisodactyle(2), and the Probosci- 

 dian divisions of the Ungulata. 



Although the structure of the molar teeth presents very 

 different degrees of complication and is much modified in the 

 Isodactyle Ungulata, it generally produces a more symmetrical 

 form or pattern of the grinding surface than in the Anisodactyle 

 division. I shall commence with the dentition of an extinct 

 genus of the Isodactyle group. 



191. Anoplotherium. — ^The Anoplothere was one of the earliest 

 forms of hoofed quadrupeds introduced upon the surface of this 

 earth, and it is characterized by the most complete system of den- 

 tition : it not only possessed incisors and canines in both jaws, 

 but these were so equably developed that they formed one un- 

 broken series with the premolars and molars, which character is 

 now found only in the Human species. 



The dental formula of the genus Anoplotherium is : — 



in. 5=^; c. J^; p. — ; m. —: = 44. (PI. 135. fig. 1—3.) 



3—3 ' 1— 1 ' '^ 4—4 ' 3-3 ^ O ^ 



Those teeth which are transitorily manifested in the embryo-state 



(1) Hoofed Quadrupeds with toes in even number, as two or four, and which have a more 

 or less comphcated stomach, with a moderate sized simple coecum. Ex. Ox, Hog, Peccari, 

 Hippopotamus. 



(2) Hoofed Quadrupeds with toes, (on the hind-foot at least,) in uneven number, as one 

 three, or five, the latter number being manifested by the Proboscidians. All these have a 

 simple stomach and an enormous coecum, Ex. Horse, Tapir, Rhinoceros, Elephant : but the 

 last Pachyderm combines, with its proboscis, so many other peculiarities of structure, as to have 

 been recognised as the type of a distinct group of Ungulata, most of the members of which group 

 are now extinct. 



