260 



SUBUNGULATA 



ORDER IX 



there are three homogeneous teeth {denies mtermedii) in each jaw, which as a 



rule exhibit three or four transverse crests. Hence they are divided into two 



sections : Trilophodon and Tetralophodon. 



1-2.2.3. 

 In the trilophodonts, the number of transverse crests is : i) 



2 2 



3.3.4. 



2.3.4. 

 in the tetralophodonts : I) : {F 



3.3.4.' " "^ " ■ 2.3.4 



The number of crests may be increased by one in exceptional cases. 



1-2.2.3. 

 2.2.^' 4.4.5. 



Fig. 345. 



Tetrahelodon longirostris Kaup sp. Lower Plio- 

 cene, Eppelsheim. The three upper milk molars. 

 1/3. (Alter Kaup.) 



Fig. 34ll. 



Stegodon clifti Falconer and Cautley. Pliocene 

 (or Pleistocene), Burma. First upper molar. 1/4- 

 c, Cement ; D, dentine. (After Clift.) 



In the Middle and Upper Miocene of Europe, also in northern Africa, 

 Tetrahelodon (Trilophodon) angustidens Cuvier and T. (Trilophodon) turicensis Schinz 

 are especially abundant. In the Lower Pliocene of Europe (Eppelsheim) 

 T. (Tetralophodon) longirostris Kaup. In the Miocene and Pliocene of North 

 America, several species of Tetrahelodon occur, but they need a thorough 

 revision. They include T. produdus Cope and T. dinotherioides Andrews in the 

 Miocene, and T. mirificus Leidy and T. tropicus Cope in the Pliocene of Texas. 



Fig. 317. 



stegodon insignis Falconer and Cautley. Pliocene, 

 Siwalik Hills, India. Vertical longitudinal section 

 of upper molar, i/g. (After Falconer and Cautley.) 



Fig. 348. 



Elephas {Loxodon) africanus Linn. Grinding 



surface of lower molar. 1/5- 



Mastodon Cuvier. Differing from Tetrahelodon in having the symphysis of 

 the mandible shortened as in Elephas, with not more than functionless remnants 

 of the lower incisors. 3f. pentelici Gaudry and other species occur in the 

 Lower Pliocene of Pikermi, Samos, and Maragha. M. horsoni Hays and 

 31. arvernensis Croizet and Jobert are characteristic of the Middle and Upper 

 Pliocene of Europe. 31. falconeri, Lydekker, sivalensis Falc. and Cautl., 

 perimensis Falc. and Cautl., punjahie7isis Lydekker, latidens Clift and other 

 species are found in the Pliocene (Siwalik formation) of India, also some in 

 China and Japan. 31. americamis Cuvier has a wide distribution in the 

 Pleistocene of North America. 31. serridens Cope, and 31. shepardi and 



