18 



Proboscidea — Mastodon americanus, etc. 



Glass-case 

 B. 



Table-case, 

 No. 23. 



Stand A. 



lieim, Hessen-Darmstadt, Germany, while others have been 

 found in Trance, Switzerland, and Perim Island, Gulf of 

 Cambay. The original skull of Dinotherium, described by Dr. 

 Kaup, together with a reproduction of the lower jaw, is placed 

 in a separate case in this gallery. (See p. 11, Fig. 10.) 



The Mastodons were elephants with 

 the grinding teeth less complex in struc- 

 ture, and adapted for masticating coarser 

 vegetable substances. The grinding sur- 

 face of the molars, instead of being cleft 

 into numerous thin plates, are divided 

 into wedge-shaped transverse ridges, and 

 the summits of these are often subdivided 

 into smaller cones, more or less resem- 

 bling the teats of a cow, whence the 

 generic name is deiived.* They are 

 divided into two groups (Trilophodonts 

 and Tetralophodonts), characterised by 

 the number of the transverse ridges in 

 the first and second true molars. In fig. 24 —Profile of outer aspect 



,, m-iii ,i -t -i, or second lett lower true molar of 



the ll'llophodonts the ridges are but Mastodon amei-icanus (Cuvier), a 



three in number, the Tetralophodonts ™? ho f ^ f ?™ from fl » pw »- 



. ' t 1 tocene of korth America (much 



having four. 



Fig. 25. — Skeleton of Mastodon americanus (Cuvier) = J/, ohioticus: (greatly reduced) 



from the Pleistocene, Benton County, Missouri, N. America. 



(See skeleton on Stand A, at entrance to South East Gallery I.) 



* From mastos, teat, and odos, tooth. 



