MAMMALIA. 



HI 



38-42. 



cases 

 23, 24. 

 Stand B. 



Tiie i'liueeiie and Pleistucene mastodous jiLst euuiaerated Pier-cases 

 clearly possessed the ordinary elephant proboscis, and would ipab^.' 

 l)e elephants to all outward ai)pearance. Young individuals, 

 however, exhibit a diminutive pair of tusks projecting from 

 tlie front of the lower jaw. They are thus reminiscent oi' 

 Iheir ^Miocene predecessors in Europe and Africa, whicli had 

 well-developed lower tusks throughout life. These ancestral 

 mastodons, of the genus Tetrahdodon,, are illustrated by 

 numerous remains from the IMiddle and Upper JVIiocene and 

 Lower Pliocene of Europe, and by one mandible from Kansas, 



Fig. 5-t. — Skeleton of Masfudon americanun, from the Pleistocene of 

 T^)enton County, Missouri, U.S.A. ; height '.) ft. Hin., length 20 ft., and 

 length of tusks 5 ft. G in. (Stand B.) 



I'.S.A., in I'ier-case 41 (42). Xone of Ibe sjx'cies were so 

 large as tlio.se of the genus M((.sfo(/o/i, itself. Their skull 

 (Fig. 60) is like that of an elepliant, aiul tbe spreading upper 

 tusks only difter from modern e]e])haiiti tusks in having a 

 band of enamel along one side. Their lower jaw, liowevei-, 

 is produced at the chin (symphysis) into a remarkable bony 

 spout-shaped elongation, tipjied with a ])air of chisel-sluiped 

 tusks, which cannot liave woi'ked against tbe u])])er tusks, 

 but exidently met some kind of ])ail on Mie palate. Tclra- 

 hrhnldii must thus liave i)Osst\ssed an iiiiiiieiiselv eloULiated 



Pier-case 

 41. 



