RUMINANTIA. 401 



potamus, and Hippohyus, had the typical dental formula, and 

 this is preserved in the existing representative of the same 

 section of non-ruminant Artiodactyles, the hog. The first true 

 molar when the permanent dentition is completed, exhibits the 

 effects of its early development in a more marked degree than 

 in most other Mammalia, and in the Wild Boar has its 

 tubercles worn down and a smooth field of dentine exposed 

 by the time the last molar has come into place ; it originally 

 bears four primary cones, with smaller subdivisions formed by 

 the wrinkled enamel, and an anterior and posterior ridge. The 

 four cones produced by the crucial impression, of which the 

 transverse part is the deepest, are repeated on the second true 

 molar with more complex shallow divisions, and a larger 

 tuberculate posterior ridge. The greater extent of the last 

 molar is chiefly produced by the development of the back ridge 

 into a cluster of tubercles ; the four primary cones being dis- 

 tinguishable on the anterior main body of the tooth. The 

 crowns of the lower molars are very similar to those above, 

 but are rather narrower, and the outer and inner basal tubercles 

 are much smaller, or are wanting ; 

 the grinding surface of the last 

 is shewn in fig. 155. 



Extinct species of hog have 

 been found in miocene beds at 

 Eppelsheim (Sus palceochcerus, Fi s- 155 - 



-T7- \ i , cr /a • Last lower molar, Hog. Nat. size. 



Kp.), and at Simorre (S. simor- ' 6 



rensis, Lt.) ; in pliocene beds (S. arvernensis, Crt), and in 

 later deposits, where the species (S. scrofa fosilis) is not dis- 

 tinguishable from the present wild boar. 



Order Kuminantia. 



Of other forms of beasts subsisting on the vegetable pro- 

 ductions of the earth, and more akin to actual European Her- 



2 D 



