MAMMALIA. 



57 



Crag and Norwich Crag, and there is one molar from a fissure tTabie-case 

 in the Chalk at Dewlish, Dorset. Photographs of the circum- 20, 

 stances under which the latter specimen was discovered are 

 fixed on the wall in the bay between Pier-cases 34, 35. 



Bemains of true elephants are quite common in the 

 Lower Pliocene Siwalik Formation and in the Pleistocene 

 river-deposits of India. All of these are closely related to 

 the living Indian elephant, but some, such as E. planifrons 

 and E. hysudricus, seem to be intermediate between the 

 surviving Indian and African species. The Cautley Collection 

 and numerous other specimens in Pier-cases 33 and 34, Table- 

 case 22, and on special stands, form a unique illustration of 

 these extinct members of the Indian fauna. 



Fier-cases 

 33, 34. 



Table-case 

 22. 



Stands O, 

 P, "W. 



Fig. 46. — Grinding surface of upper molar tooth of Elephas meridionalis, 

 from the Upper Pliocene of Tuscany; one-third nat. size. (Table- 

 easel 20.) i 



The Indian species just mentioned are the earliest known 

 examples of the true elephant, which thus makes its first 

 appearance in the Lower Pliocene of Asia. With the typical 

 kinds are associated other elephants which possess more 

 primitive grinding teeth, and show how the elephantine 

 molar originated. They prove, in fact, that this ponderous 

 tooth has gradually arisen in the elephant tribe by the 

 enlargement and complication of a tooth with a few cross- 

 ridges. The first stage (among elephants with a normal 

 proboscis or trunk) is found in Mastodon (" nipple-tooth "), 

 which is represented by M. sivalensis (Fig. 50) and other 

 species in the Siwalik Formation (see Pier-cases 36, 37, and 

 Table-case 23). A longitudinal vertical section of this kind 

 of tooth (Fig. 47) displays the thick cross-ridges separated 

 by wide valleys, which are quite empty or only partially 

 blocked by small supplementary knobs or ridges. The next 

 stage, named Stegodon (" roof-tooth ") in allusion to the 



Fier-cases 

 36, 37. 



Table-case 



