524 UNGULATES. 



of the Ruminant, as the upper incisors and canines(l) and the 

 anterior premolars, were, in the ancient Anoplothere, retained 

 and raised to proportional equality with the rest of the teeth. 

 What is suppressed in the Ruminant Order is developed in excess 

 in other Isodactyle Herbivora, as, for example, in the Hippopotamus 

 and Babyroussa ; and almost every kind and degree of variety, save 

 that of increased number of teeth, has been superinduced in later 

 and existing forms of hoofed Mammals upon the primitive Ano- 

 plotherian formula, which may therefore be regarded as the type 

 or perfect standard of the dentition of the great natural group of 

 TJngulata. 



In the Anoplotherium commune{2) the upper mid-incisor has a semi- 

 elUptic crown, very convex externally, with a large root expanded near 

 the neck : the second and third incisors have the end of the crown 

 slightly produced giving it a triangular form : all three have a small 

 cusp at the outer border. The canine differs in the greater breadth 

 and thickness, but not in the length of the crown ; the middle part 

 of which forms a low cone with well-marked basal angles. In the 

 first upper premolar (PI. 135, fig. 2, p 1) the anterior angle is more 

 developed, and the principal lobe has an internal basal ridge : the 

 outer surface is sinuous, convex in the middle, and the entire 

 tooth is enlarged. In the second premolar (ib. p 2) the depression 

 between the more developed inner basal ridge and the main lobe 

 is deepened, and forms a long enamel-island when the crown is 

 much worn : a second basal ridge is also developed below the former 

 in this and the next premolar (ib. p 3), which, with the fourth 

 (ib. p 4), progressively increase in size. The true molars (ib. m) 

 have thicker square crowns which present the following characters : 

 a transverse valley (6) extending, from within, two-thirds across, 

 divides the crown into an anterior (o) and a posterior (c) lobe which 

 are continuous along the outer border of the tooth : an antero- 

 posterior valley (c, e) crosses the termination of the first, penetrating 



(1) Goodsir, Report of British Association, 1838. 



(2) This animal was the size of an Ass, and, with the other species of the extinct genus, 

 had a cloven-hoof, like the Ruminants, but the division extended through the metacarpus and 

 metatarsus. The Anoplothere was an animal of aquatic habits and had a very long and strong 

 tail which Cuvier conjectures to have been used like that of the Otter in swimming. 



